(FOREST FIRE-DANGER MEASUREMENT

IN THE

EASTERN UNITED STATES

By

GEORGE M. ¿EMISON, Silviculturist, A. W. LINDENMUTH, Forester,

and J. J. KEETCH, Forester, Forest Service

v/ Agriculture Handbook No. I

UNITED STATES DEPARTMENT OF AGRICULTURE

V Forest Service

For sale by the Superintendent of Documents, U. S. Government Prtotlng Office

Washington 25, D. C. • Price 25 cents
§üby4V

FOREST FIRE-DANGER MEASUREMENT

IN THE EASTERN UNITED STATES

By GEOKGK INI. JKMISON, Silrioultifrist^ and A. W. LINDENMUTH, ForcHter Soiifkea^tvrn Forest Experiment Station, jind J. .7. KKETCIT, Forester, Reqion 7

Forest Service '

CONTENTS

Puyt

Introduction... 1

The principles of nieítóurinR forest ííre danfiêr' 4

The key fire-danger factors 4

Fuel moisture content 4

Wind 1]!"]" ñ

Condition of vegetation ó

Season of the year ó

Systematic measurement of the k^y factors. 7

Integration of measurements of the key

factors 7

Specific uses of fire-danger ratings 12

Application in fire prevention 12

Use of fire-danger ratings in presuppi-ession. I'l

Fire-danger ratings used in suppression is

Danger ratings applied to damage appraisal. 1 s

Danger rating and prescribed burning 19

Operation of a fire-danger measuring system.. U)

Selection of fire-danger station location ly

Number 19

Exposure 20

Equipment used in fire-danger measurement

and its installation 21

Ground plan for danger station as a

whole 21

Fuel-moisture indicator sticks 21

Fuel-moisture scale 2:^

Weighing shelter.. 2.".

Rain gages and supports. 2f;

Anemometers 28

Page

Operation of a fire-danger measuring systemContinued

When to measure weather and fuel factors.. 29

Taking measurements and rating fire dan-

^ ger 31

Summarizing fire-danger records 3i

Predicting tomorrow's fire danger 32

Training and inspection 33

Literature cited 34

Appendix 35

Instructions for observers at fire-danger stations 35

Itemized list of equipment and mateiials for

a fire-danger station 4r>

Bill of materials for weighing shelter 4.'')

Partial list of suppliers of fire-weather equipment 46

Routine for cleaning anemometers 47

Wind correction charts for dilTerent types of

anemometers rú

Preparation and distrit)Ution of fire-danger

daily record and fire-danger daily summary 59

Points to follow in opening an intermittent

fire-danger station 64

J'oints to follow in closing an intermittent

fire-danger station 65

lnsi)ector's report—fire-danger station inspection 66

INTRODUCTION

Is today a bad fire day, only inodeiately bad, or just an averao:e day

for the season'^ The fire-danger^ rating system described in this

publication answers that question daily at -ilo locations in the 24

States in the East from Maine to Texas (fig. 1).

Fire-danger ratings are reliable because of the careful researcli and

experience apj^lied in developing the system and the accurate information used in the daily computations. Several times a day measurements of fuel moisture and W'ind velocity are made at each danger

1 <'Fire danger" is a general term expressing the sum total of both the constant and the variable factors which determine whether fires will start, spread,

and do damage, and that determine their diflaculty of control. In this pul)lication "tire dan;^er" is used narrowly and refers only to the variable asi)ects of

fire danger such as weather and fuel moisture. Complete definitions of other

common fire-control terms may lie found in Glossary of Terms Used in Forest

Fire Control (22) (see Literature Cited, p. 34).

United States Department of Agriculture

Agriculture Handbook No. 1

Issued December 1949
HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Figure 1.—Location of stations in eastern United States.

station in the woods. Precipitation is also recorded. These measurements, combined with season of year and condition of vegetation, form

the basis for rating the day's 'fire danger. By using a fire-danger

meter, wliich automatically gives the key factors their proper weight,

the operator of a danger station can determine the type of fire day

quickly, accurately, and without personal bias. The'ratings are expressed in numerical classes having definite meaning and callino- for

definite action.
FOiXEIST FIRE-DANGER MEASUREMENT 3

Before this system was dovelojKMl, fire control officers tried to estimate the day's burning conditions according to certain rough rules of

thumb. Wind velocity was estimated from the movement of trees

or smoke drift. The extent to which a pine needle would bend without breaking or the ease with which hardwood leaves would crush

in the hand are exam])les of various attempts to find some basis for

an opinion of burning conditions. These rules were derived from

popular ex])erience and were higldy useful to an exi)erienced man in

an area familiar to him.

From such observations and from work on going fires, the experienced old-time foivster could estimate the peak periods of danger

in a limited area. He could not tell what the conditions were in remote areas, nor could he refine his observations to judge the wide

range of burning conditions that exist between the times when the

woods are relatively safe or extremely hazardous.

Today the forester measures the amount of moisture and wind

velocity with instruments, and he includes other important factors

not considered by the old-timer. Observers will report to him periodically from several points on tlie forest, and he has a picture of forestwide conditions at intervals during each day. He can be sure that

the reports from all stations are comjxirable, and that any individual

record is not aifected by the observeI's opinion on that day, or his

past experience in fire control, or lack of it.

The idea of measuring foi'est fire danger originated about 15 years

ago in the Northern Rocky Mountains when (nsborne {S)~ constructed

a fire-danger meter that expressed the degree of danger in numerical

classes, based on measurements of certain fuel, weather, and other

factors. Considerable study of individual weather factors and their

relation to infiannnabilitv preceded or accompanied the development

of the first fire-danger rating system (6', /•, 9,10,15,16,17,19, and 21),

During the lOoO's almost every Forest Service region was testing

fire-danger measurement.

Fire-danger ratings are a useful tool in the job of prevention and

control and represent a tremendous advance over the informal and

uninformeci methods of guessing at danger, conmion a decade or two

ago. Even so, there are many ways in which future study can improve

the present ratings. Danger measurements aid but do not replace

experiencecl judgment. The fire-danger rating system for the eastern

United States ^ described in this publication has been developed and

tested over a 10-year period. Its usefulness as a tool in fire control

has become w^ell' established. If properly used, the results can be

adopted as a practical guide in fire control planning with full assurance

that the most impcji-tant variables affecting fire danger from the

weather standpoint are accounted for.

' Numhers in italics refer t<» Literature Cited, p. 34.

' For the purpose <»f this discussion, "e.-istern United States" includes the Northeastei-n States, the Cuuil)erhuid and Alieuheny plateaus and adjacent lowlands,

the Appalachian mountain system, the Piedmont phiteau, and adjacent Coastal

Plain. It includes portions of the deep South, but none of the Lake States or

Central States.
4 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

THE PRINCIPLES OF MEASURING FOREST FIRE

DANGER

In the eastern United States the danger-rating system has been developed as an index of forest inflammability, i. e., the relative ease

with which fuels ignite and burn.. Two closely related systems are

in use—one for the Northeastern States and plateau and mountainous

sections, which are primarily hardwood-covered, and the other for the

adjacent Coastal Plain and Piedmont pineland sections of the South

and Southeast (exclusive of the longleaf-slash pine forest type) {!).

THE KEY FIRE-DANGER FACTORS

Four key factors have been found to determine fire danger in the

mountains and three in the Coastal Plain. These are (1) fuel nioisture content determined from wood sticks and number oi days since

rain, (2) wind, (3) condition of vegetation, and (4) season of 3^ear;

the latter factor being relatively unimportant in the Coastal Plain.

FUEL MOISTURE CONTENT

Moisture content of fuels, a controlling fire-danger factor, is particularly important in lightweight material such as dead grass, hardwood leaves, weeds, and pine needles. Fire brands ignite this material

first and it burns most rapidly.

The moisture content of these lightweight fuels changes rapidly

as weather fluctuates, but the relation is so complex that moistures

cannot easily or accurately be determined from measurement of atmospheric factors such as humidity, temperature, and evaporation.

Experience has proved that even the most experienced men cannot

sense changes of a few percent in fuel moisture content which may

make considerable difference in inflammability.

One simple and inexpenslAe way to measure fuel moisture is by

means of fuel-moisture indicator sticks. Different sizes, shapes, and

kinds of indicators are used in the United States, but flat slats 18

inches long, made of basswood, have been found to work best in the

East. These sticks, when exposed under typical forest conditions,

reveal the effect^ in one simple measurement, of all controls (the

causes) of moisture content, such as precipitation, humidity, temperature, evaporation, solar radiation, and wind. The fuel-moisture sticks

do not always indicate the exact moisture content of natural fuel,

but the relation between indicated and actual moisture is relatively

constant. In general, the sticks dry out slightly faster than natural

fuel after a rain and thus give some forewarning of approaching

dangerous conditions.

The method of determining fuel moisture consists essentially of

exposing under natural conditions a set of three numbered basswood sticks, for which the oven-dry weight has been predetermined,

and weighing them currently on a specially constructed scale. This

scale shows average moisture content directly.

Although the wood sticks provide excellent measures of current

changes in the light fuels, they do not reflect the cumulative build-up

of inflammable conditions in heavier fuels, denser "rough," and deeper
FOREST FIRE-DANGER MEASUREMENT 5

layers of hardwood leaves, resiiltino^ from several days of dry weather.

'\Anien these classes of fuel become dry, fires burn hotter, are harder

to control, and require more mop-u]) work. But here, also, a means

of appraisino' inflammability has been determined. It has been found

that the number of days ela])sed since rains of different amounts is a

useful index of cumulative drying. The effect of showers (less than

0.25 inch) is adequately measured by the fuel-moistiiiv sticks. Hence,

the build-up of danoer is indicated by days since rains of 0.25 inch or

more.

Because of differences between mountaiii hardwoods and Coastal

Plain pine-woods fuel types, this factor is of less importance in the

Coastal Plain regions, particulai'ly in the winter and spring seasons.

Although time since rain is an easy and practical way to evaluate

cumulative drying, it is not an exact measure. Considerable study

will be I'equired to improve the measurement of this factor.

WIND

Measurements of wind velocity are important because wind velocity

is difficult to estimate and is of first importance in affecting rate of

spread if fuels are dry enough to burn. Measurements of velocity

can be made with any one of a number of buzzer-type anemometers.

Because Coastal Plain fuels (principally dead grass) are finely divided

and exposed to the air, wind velocity must be given more weight in

the flatwoods than in mountain forests.

CONDITION OF VEGETATION

The state of the ])hysiological activity of plants, varying with

latitude, elevation, and aspect, is another factor which contributes to

the degree of fire danger. For exam]:)le, grasses, weeds, and shrubs

tend to retard the rate of spread of fire as long as they are succulent

and transpire large quantities of moisture; but when they are dry

their effect on fire behavior is reversed. This difference in inñammability resulting from i^hysiological condition is outstanding in the

pine forests in the lower country where grass is a primary fuel.

Transition periods, when vegetation is coming up in the spring or

when it is curing in the fall, are intermediate in their effect on fire

danger. In some sections of the eastern Ignited States this transition

is very gradual in the fall ; in others it is very abrupt, owing to sudden,

heavy autumn frosts.

SEASON OF THE YEAR

The intensity of solar radiation obviously determines the drying

rate of forest fuels, and since it varies with the calendar, the season

of the year becomes an important fire-danger factor. This is particularly true in mountainous or hilly country where the movement of the

sun towards the zenith as spring and summer api)roach causes more

rapid and complete drying on north slopes. In fall and winter, north

slopes often act as good firebreaks because sunlight reaches the

ground for only a few hours each day or perhaps not at all (S), In

the flat country such effects do not exist, of course, and season of the

year is not important.
6 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Season of the year is also a direct measure of length of day. Durino^ summer months the days are long, and with more hours of sunlight, fuels tend toward low moisture levels for longer -periods. In

the summer, shade of a hardwood overstory somewhat reduces the

effect of long days because dead ground fuels are not exposed to sunlight at all. Length of day is a factor during the leafless seasons,

however. Long, cool, humid nights at this time of year create more

favorable conditions, of course, and the burning day is considerably

shorter. This is particularly true at northern latitudes, where the

length of day may change 7 or 8 hours in the course of the year.

Even in the southernmost ])art of the Appalachian region, length of

day changes 4 to 5 hours from winter to summer.

Figure 2.—A typical fire-danger station where fuel moisture and wind velocity are

measured. Precipitation is measured in the open, away from sheltering trees.
FOREST FIRE-DANGER MEASUREMENT 7

SYSTEMATIC MEASUREMENT OF THE KEY FACTORS

Fire danger is ordinarily determined from measurements taken

several times a day at a network of stations so located as to sample

major variations in fire weather caused by toy)oo;raphy and other

physical features. A complete description of the selection of iiiedano'er station locations is <>;iveii on pa<>:es 11) to 21. A typical Hredano-er station consists of a fuel-moisture scale housed in a weighing;

shelter, a set of fuel-moisture indicator sticks, an anemometer, and a

rain gage as basic equipment (fig. 2). A complete itemized list of all

miscellaneous equipment and materials is included in the Appendix.

Measurements of fuel moisture and wind velocity, two or three

times a day, and of rain once a day provide the data necessary to follow the development of critical conditions as well as to obtain an

accurate average daily danger rating. A towerman, guard, or weather

observer can read the instruments and record the observations in about

5 minutes. (See pp. 38 to 44 for explanation of the procedure.) Some

agencies prefer to follow the changes in danger more closely and

require observers to take as many as six readings a day during critical

periods.

INTEGRATION OF MEASUREMENTS OF THE KEY

FACTORS

Current measurements of the key fire-clanger factors are integrated

into numerical classes or index numbers by means of two danger

meters, one for the mountain region, the other for the Coastal Plain.

The mountain meter (type 5-W; fig. 3) is made in the form of a circular slide rule, and the Coastal Plain meter (type 7; fig. 4) consists

of an envelope and movable slide. Both meters rate fire danger in 5

numerical classes, but the mountain meter also gives equivalent numerical ratings on a 100-point scale. The 100-point scale has been

named "basic burning index'' because it ex])resses relative inflammability w^hich is basic to hre occui-reuce and fire behavior. As figure 3

illustrates, the r)-point scale and the lOO-point index are side by side on

the meter and one can be translated directly into terms of the other.

In 1937, when plans for developing a fire-danger rating system

were being made, many experieiiced fire control men felt that only two

danger classes could be recognized. This feeling was sunmied up as,

"The woods will either burn or they won't burn." After a 5-point

scale had been devised and used for several yeare, however, experience

showed that there were even more than five recognizable classes of

danger. There were more than five separate and distinct steps that

could be taken to organize for conditions ranging from "safe" to the

very Avorst. Protection men talked of "low^ class 3," "high class 2," or

"middle class 4."

It was this demand for a greater refinement in expressing danger

that led to the development of a 100-point scale. This scale shows the

gradual build-up of serious danger more effectively than the 5-point

scale, as is illustrated by the following tabulation for the period May

2 to 12, 1947, at the Trout Run Station, George Washington National

Forest, Va.
HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Haling

6-po'mt scale lOO-poinl scale

1947 May ' (rf"««) (Jmrnino index)

'2__1' 1 2

3 2 11

4 3 13

5 3 17

6 3 25

7 3 15

8 4 40

9 4 40

10 4 40

11. 4 45

12 4 75

F-454I04

Figure 3.—The mountain meter, a circular slide rule for integrating fuel moisture

and weather measurements into numerical danger classes.
Burning Index

Approximate

midpoint

1

5

20

65

100

Range

1 to 2

3 to 11

12 to 35

40 to 95

100 +

FOREST FIRE-DANGER MEASUREMENT 9

Note how the basic burning index for elass-3 days ranged from 13 to

25 and for class-4 days showed a build-up from 40 to 75.

The 100-point basic burning index as used on the mountain meter

has another advantage over the ö-point scale in that it bears a straightline relation to relative inflammability when fire occurrence is used

as a measure of inflanuiiability (fig. 5). Note that on a class-:> day

(fig. 5, Ä) the relative number of fires is 6.6. Thus, a burning index of

21 (fig. 5,5) is the equivalent of a class 3 because it also sliows 6.6 fires.

The relation between class of day and burning index is given below,

with the midpoints rounded to the closest unit of 5 points.

100-point scale (Meter 6-W)

6-point scale

Class:

1

2

3

4

5-

A basic burning index of 40 represents conditions twice as bad as

one of 20. A day rating an index of 10 is only half as bad as one

rating 20. But a class 4 on the 5-point scale is not twice as bad as a

class-2 rating. Itis approximately 13 times a class 2 if fire occurrence

in figure 5 is used as the basis of comparison. The advantages of the

straight-line relation of the basic burning index to inflammability will

be explained further in the discussion of summarizing danger ratings

(see p. 31).

The straight-line, or proportional, relationship between the rated

inflammability of forest fuels and the number of fires likely to occur

is a highly important relationship in the value of the danger ratings.

But it must not be misconstrued. If, for example, 50 careless smokers

were discarding the same number of lighted matches into exactly the

same forest fuels at similar locations over a period of several days or

weeks, the number of fires that would start each day and that would

require control action by the fire organization would vary in proportion

to the variations in the burning-index rating for the day, as in figure

5, B. If on the average 1 fire resulted at a rating of 20, 2 fires could

be expected at a rating of 40, 3 at 60, etc. However, from the tabulation above, if class-1 conditions under such circumstances resulted

in 1 fire on the average, 5 fires could be expected under a class-2

rating, and 20 under a class-3 rating.

Such relationships hold only so long as the exposure of forest fuels

to sources of fire remains the same. This is closely aj^proached when

the number of fires at various danger ratings are combined for very

large areas, such as a group of States or a region, or are developed

for a single protection unit over a long period. It will also be closely

approached when the fire risk is constant in even small areas, such

as along a railroad right-of-way, around a constantly operated refuse

burner, and so on.

848722'—50 2
10 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

The number of fires that may be maliciously set will naturally deviate from these trends for accidental fires, since they represent an

erratic and independent source of risk. Consequently the time, place,

and number must be anticipated by other criteria. Even so, the

success of the incendiai'ist in getting a large number of sets to ' take

and to spread rapidly enough to burn over sizeable areas before they

F-454105

Figure 4.—The Coastal Plain danger meter is of regular slide-rule design. It integrates fuel moisture and weather data into five possible danger classes.

can be controlled will depend on the burning conditions at the time

and will closely reflect the burning index which expresses these

conditions.

Lightning fires, which are important in only a few localities in

the South, luive somewhat similar relationships. Fire-setting lightning storms are usually erratic in occurrence, but the number and

size of fires that result and the consequent size of the fire-fighting

job will also be closely related to the burning conditions at the time

they are started and until they are extinguished. AAliether or not

any will occur must also be determined by other criteria.
FOREST FIRE-DANGER MEASUREMENT 11

On a single protection unit, the tires to be expected from the normal

and more or less constant sonrces of risk at different burning-index

ratings can soon be established. From this as a base, both the success

of prevention effort and the importance of new and variable sources

of fíre risk can be evaluated and used in the planning and management of the fire organization.

After additional study the 100-])oint scale will l)e adapted to the

Goastal Plain meter. For this meter, the upper limit of the new scale,

the 100-point, should be placed to represent more dangerous conditions than it does on the mountain meter. This is necessary because,

in the pine forests of the fiatwoods, the fuels dry out faster and are

exposed to higher winds. The beneficial effects of rains are quickly

dissipated. There is a need to be able to identify and evaluate the

50 50

40 / 40

i

A ^

B

b» / O 30 y^

1

/ 1

^20

Í X

/

^20

y^ ^

i! / Ci y'^

<t et

10 / IG y^

66

/

6.6 >y<^

^^^+

/\ ,T °() 1 2 3 4 ^5 ^ 3 20 40 60 80 100

FIRE DANGER CLASS BASIC BURNING INDEX

Figure 5.—Relation between fire occurrence and fire danger expressed on {A) 5-

and (JB) 100-point scales. Based on records for 14 Northeastern States, 1942 to

1945.

extreme conditions îhat occur more frequently than in the mountain

hardwood forests.

The factors integrated into the danger classes or burning indexes

by the mountain meter are (1) fuel moisture as indicated by wood

sticks and days since last rain, (2) wind velocity, (3) condition of

lesser vegetation, and (4) season of year. The ''season of year''

factor is not of sufficient importance to require consideration on

the Coastal Plain meter; and because of regional variations in climate,

latitude, elevation, and forest types, the other factors are given diff'erent weights on the two meters.

Predictions of fire danger for at least a 24-hour advance period are

desirable because of the characteristic rapid and frequent fluctuations

in danger that make it difficult for fire control men to estimate class

of danger for the future. The first models of the danger meters

included a device for forecasting ''tomorrow's'^ fire danger, essentially

by modifying current danger on the basis of predicted weather and

wind. Extensive tests have shown that this feature could be relied

upon to forecast danger with a satisfactory degi^ee of accuracy m

most parts of the Eastern States, but unfortunately the prediction
12 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

required considerable local adjustment in the mountains. Because of

this impracticability, the forecasting feature has been eliminated on

the mountain danger meter but not on the Coastal Plain meter. Fire

danger may still be predicted by an experienced man, however, using

this meter with a forecast of Avind and weather supplied by the

Weather Bureau. Estimates of fuel moisture content are based upon

such predictions and the local forester's intimate knowledge of the

relation of fuel moisture to temperature, humidity, cloudiness, and

other weather factors.

Eecently two of the eastern offices of the Weather Bureau began

experimental predictions of fuel moisture content. If forecasters

study the relation of fuel moisture to weather and are equipped with

the best available guides for estimating probable absolute humidities,

radiation effects, and other phenomena, they may be in a better position than the forest officer to predict fuel moisture. The present tests

have not run long enough to indicate whether or not fuel moisture

predictions from a central Weather Bureau office are more or less

reliable than on-the-ground estimates.

SPECIFIC USES OF FIRE-DANGER RATINGS

A danger rating based primarily on fuel moisture and wind is an

accurate index of inflammability—the relative ease with which fuels

ignite and burn. It can be used to indicate probable fire occurrence,

fire behavior, difficulty of suppression, and damage. However, other

factors not measured in the danger-rating system also affect these

phenomena. Hence, considerable care and understanding are necessary in using fire-danger ratings ^ as a guide to fire protection activities.

Some of the principal uses of danger ratings which are based on fuel

moisture and wind are discussed on the following pages and their limitations pointed out.

APPLICATION IN FIRE PREVENTION

In the East, where 98 percent of the fires are man-caused, there is a

definite relationship between occurrence and fire-danger ratings

(table 1). Most debris burning, such as tobacco-bed burning or other

clean-up connected with agriculture, is seasonal and is done in dry or

moderately dry weather. Incendiarists tend to operate in dry weather

too. Some fire-starting agencies, such as railroads and smokers, are

active rain or shine. Even so, there is about 65 times more chance for

a fire to occur on a class-4 day (for a system of rating on a scale of

1 to 5) than on a class-1 day in the eastern United States as a whole,

as shown in the tabulation on page 9. This ratio varies for different

parts of the country. Thus, fire-danger ratings can be used to indicate relative ignitibility of similar fuels.

In any test of the effectiveness of a fire-prevention campaign, the

danger existing during the period must be considered, otherwise a

reduction in the number of man-caused fires due to favorable weather.

'^ Additional information on different kinds of danger ratin,^•s and the elements

of each may be found in Forest Fire Danger Indexes, by Jemison {12).
FOREST FIRE-DANGER MEASUREMENT 13

conditions mi^lit be mistaken for <>;()od prevention technique. Or, conversely, if the lire weather was critical, prevention eñorts may have

t)aid off even thong'h numbers of fires were not reduced over previous

ess dangerous periods. Conditions that influence the ease of ignition

should be considered in studies of the elliciency of prevention work, if

fire-danger ratings are available.

TABLE 1.—A re tut qc vumher offires per danqer-claHH day for IJf EoMtern

jStafes, October lOJß to December lOp '

State

Fire-danger-class day

Total

fires,

basis 1 2 3 4 5

Connecticut

Delaware 2

Kentucky ^-_

Nu tuber

0.3

.04

. 02

.3

. 2

.6

. 4

. 4

. 2

. 4

. 2

. 1

. 4

. 4

Number

1. 6

2

^3

1. 3

1. 1

1. 9

1.0

2. 2

.9

1. 6

.5

. 4

1. 9

]. 5

Nu tuber

9.8

. 4

1.9

4. 6

5.2

11. 7

5. 2

7. 5

3. 5

9. 7

1. 8

2. 4

13.2

9. 3

Nutuber

27. 8

1. 1

3.2

11.5

20. 5

32. 2

17.8

28. 2

10. 5

52. 9

6. 7

4.3

52. 0

24. 7

Number

"'52.0'

"""67.'7~

122. 2

Nu tuber

4, 570

209

685

Maine 1,854

Maryland * 3,768

Ma,ssachusetts ^

New Hampshire

New Jersey

6, 591

2, 189

6, 869

New York 6 1,825

Pennsj'^lvania 8,468

Rhode Island _

1,693

Vermont 716

Virginia 10, 428

West Virginia 5,729

All States . 3 1.3 6.9 22. 2 7 69. 2 55, 594

1 Does not include fires that burned on days of unknown danger class.

2 1943-45 only

3 1 fire district'through 1944, 4 districts 1945, 3 districts 1946, 5 districts 1947.

^ 1945 not included.

5 Western district not included in 1946 and 1947.

6 Adirondacks and Long Island only.

7 Only 5 class-5 days recorded 1942 to 1947.

The actual results of the war and postwar fire prevention work in

Tidewater Virginia, illustrate this use. In 1043 the Dismal Swamp

and environs were unprotected but, as a security measure, fire protection was organized and prevention stressed, with a satisfactory reduction in actual number of fires over a 5-year period. AV a s this improved condition the result of successful prevention or of favorable

weather ? Danger ratings were available for the period and the basic

relation with expected fire occurrence, already described ni connection with figure 5, was known. Consequently, the effectiveness ot

prevention could be established, as brought out in the followmg tabulation for the spring fire season in southeastern Virginia. Here it is

shown that the actual number of fires in the Southeast District decreased steadily. During the same period, the expected number ot

fires for the district, as calculated from the local relationship tor a

long period between fire occurrence and fire-danger ratings, increased

because of more critical conditions of inflammability.
14 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Number of spring flres^

Actual JJXI) e ctcd

^^"^943 ^ 74 int4 :::::: ^i» ^^^

1945 l^^'S 109

104G ::::::_: 107 104

1947::::::::!-;" ss m

Danger ratings serve as useful guides to officials whose duty it is to

open or close the woods for visitors, and to restrict smoking, debris

burning, or campfires. Numerical danger ratings are readily understood by the average layman and can therefore be advantageously used

to educate hunters, campers, fishermen, and tourists. These people are

willing to be extra careful on bad days if they know that the definition

of a "bad" fire day is based on something more than a mere guess.

Ratings have much public appeal when presented in showy form.

Fire-danger display boards, colored flags similar to storm warnings,

and a large variety of showy displays have been worked out on the

basis of measured fire-danger classes to educate and interest the general

public and users of the forests. In New England and other parts of

eastern United States, fire-danger information with suitable explanatory warnings is commonly put on the air by radio broadcasting

companies.

In the eastern United States and the South, where recreation and

other forms of public use are especially important, national forests,

national parks, Indian reservations, State departments, and many

private agencies individually practice fire preveiition to some extent.

With so many different organizations functioning, reasonable uniformity in regulating the use of fire is essential. In 14 Eastern

States (table 2), 1942-47, 85 percent of the debris-burning fires that

"got away'' did so on class-3, -4, or -5 days in spite of a'ctive burning

permit systems in most States. These fires burned 133,665 acres out of

146,541 acres burned by this class of fire. In a portion of one State

in the southern Appalachians, 76 percent of fires that escaped from

del)ris burners over a 6-year period did so on class-4 and -5 days, the

two highest danger classes. These instances would indicate that more

rigid control over issuance of permits is needed.

TABLE 2.—Numher of dehns-hvrnhig ßres^ total area 'burned^ and

average size of fire^ by fire-danger cJasHes in IJf Eastern States^

19Jt2-Ji7

Fire-danger class Fires Area burned Average size

of fire

1 _ _ _

N^inn her

222

1, 206

4, 670

3, 575

7

Acres

1,437

11,439

67, 347

66, 180

138

Acres

6 5

2

3 _____ ___ ___

9.5

14 4

4 18 5

5 _____ _ IQ 7

All classes 9,680 146, 541 15 1
FÜREST FIRE-DANCÍER MEASUREMENT 15

USE OF FIRE-DANGER RATINGS IN PRESUPPRESSION

A summary of the uses of danoer ratings in presui)|)ression follows:

1. Fire-danger ratings can be used in t3uilding np or cutting down

a presuppression organization as weather and oilier temporary aspects of hre danger change. When a man in charge of tire control

hires guards and lookout men by the day, employing tliem only when

it is ''dry,'' and dejHmding on his own or someone else's juclgment,

sometimes men are on the job when they are not net^hnl and at other

times they are not available when they should be. With an organization planned to function on the basis of fire-danger ratings, however,

lookout men, patrolmen, guards, and crews go on fire duty when they

are needed. Likewise during periods of low danger these men can be

safely used on nonfire projects.

If fire danger actually differs between ranger or warden districts,

then the operation of lookout towers varies correspondingly, and the

district dry enough to have fires has its lookout points manned. When

such a flexible scheme of fire organization duty is established in

relation to fire danger, the fire executive has some basis for auditing

administrative performance and laxness in plan execution. An illustration of the use of danger ratings to guide the build-up of a fire

organization is given in figure 6. The importance of having men and

equipment on hand at the right time is further emphasized by average

area-burned and suppression-cost figures. Those for Virginia, 1942-

46, based on 8,75U fires are as follows :

Si:e and cost

Fire-dan^cr class:

1

2

3

4

5

AveTdiH fircii

burnt (1 ¡xr

. Ire rage sapprissinn cost

InI

(acres)

per lire

{dollars)

7 9. 78

11 15. 42

21 19. 41

44 28. 61

2. The operation of a fire-danger rating scheme shows up the unseasonable or otherwise unexpected periods of dangei'ous fii'e weather.

This is good insurance against off'-season let-downs and other forms

of unpreparedness on the part of the fire organization. In some sections of the country, long fire seasons are not as common as shoit periods of high fire danger occurring throughout the year. Some of the

most disastrous fires have resulted from the inability of fire men to

recognize the development of a dangerous period in time to be prepared

for it. Such was true in parts of New England in October 1047, when

about 220,000 acres were burned and 16 people lost their lives in Maine

(24) after the fire season was thought by some of the township fire

control forces to have ended. Following a soaking rain on September

22, fire danger gradually built up to explosive conditions by October

21, as shown by these average ratings from three fire-danger stations

adjacent to the troubled area :

Fire-ihuKjer

D.-itcs—Continiu'rt f'''-^'"

Oct. 23 and 1'4_

Firc-(J(in(/cr

Dates : ^'^"'' '

Sept. 23 to Oct. 0 2

Oct. 7 to Oct. 13 3

Oct. 14 to Oct. 2(» 4

Oct. 21 «^

Oct. 22 4

Oct. 25 to Nov. 3 4

Nov. 4 to Nov. 1(1 3

Nov. 11 to Nov. 17 2
16 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

STATE FIRE WARDEN

* DISTRICT RANGER

O TOWN FIRE WARDEN

(§) CENTRAL DISPATCHER

® FIRE TOWER

CLASS 3

STATE FIRE WARDEN

* DISTRICT RANGER

O TOWN FIRE WARDEN

(CO) CENTRAL DISPATCHER

® FIRE TOWER

A FIRE PATROLMAN

• FIRE COMPANY

O PUBLIC WORKS GARAGE

O STATE FIRE TRUCK

f CIVIL AIR PATROL

^ STATE FIRE WARDEN

r DISTRICT RANGER

• j O TOWN FIRE WARDEN

• ••'u-, @ CENTRAL DISPATCHER

® FIRE TOWER

A FIRE PATROLMAN

• FIRE COMPANY

^ STATE FIRE WARDEN

• DISTRICT RANGER

O TOWN FIRE WARDEN

(co) CENTRAL DISPATCHER

® FIRE TOWER

A FIRE PATROLMAN

• FIRE COMPANY

O PUBLIC WORKS GARAGE

a STATE FIRE TRUCK

"f CIVIL AIR PATROL

STATE POLICE BARRACKS

Figure 6.—The organization plan for Rhode Island based on measured fire danger.

This is an illustration of the use of fire-danger ratings to intensify preparedness

as fire danger increases.

A, The regular organization is available. Burning permits issued without

restriction. Eleven tire-^^•eather broadcasts made daily during the spring fire

season from six commercial stations.

B, Fire patrolmen, fire companies, and deputy fire wardens supplement the

regular organization. Burning permits restricted.

C, The civil air patrol, State fire truck crews, and maintenance crews at State

garages stand by. No burning permits issued ; all outstanding permits canceled.

D, State police supplement the forest fire patrol. All organized fire suppression

crews stand by. The size of initial attack forces is increased. The public may

be banned from all forests by Governor's proclamation.

3. Danger ratings assist a new man or even an old-timer in new

country to become familiar with his fire job without having to learn

by costly experience. He may analyze past records and see what

actual fires have done under specific measured conditions. He can

understand and interpret such records, being sure that they are not

influenced by someone's personal opinions.

4. Fire-danger ratings which are numerical indexes and not indefinite terms like "good," "bad," or "very bad" permit comparisons

of the severity of conditions in two or more districts, forests. States,

or regions. Thus the accomplishments of different administrative
FOREST FIRE-DAJMGER MEASUREMENT 17

units can be balanced a<;anist the seriousness of fuel and weather conditions under which each organization worked. Foi' example, scarcity

of fires and smallness of area burned liave often been misconstrued as

evidence of oood fire prevention and suppression, whei'eas the real reason was very favorable weather. Conversely, a <j;ood fire record mi<2:ht

be taken to indicate an easy fire ])r()blem, whereas the accomplishment

was really the result of exceptionally fine work by the fire-control organization in spite of critical weather. Obviously the efficiency of

a fire-control organization should not l)e judged only on the basis of

fires and acres burned.

5. Fire-danger ratings, or even a tally of days in the higher danger

classes, make possible useful comparisons of seriousness of fire seasons

by years for any unit. It is quite useful to be able to compare a current year's accomplishments in fire control with those of past years.

Also, in planning the financial aspects of fire control, it is desirable

to know the frequency of critical and easy years. Danger ratings form

a valid basis for such a classification. For example, on the Cumberland and Monongahela National Forests, the number of class-3 or

higher days has varied as follows :

Total number ofclass-S, -4, and -6 days

Ciiinherland Monongahela

National National

Year : Forest Forest

1942 (October to December onlv) 60 56

1943 130 100

1944 121 63

1945 73 79

1946 89 123

1947 .____.__. 66 79

Comparisons of average weighted danger ratings are even more useful

because they give weighted values that reflect likelihood of fire occurrence.

Current fire control funds are allotted by the Forest Service to

various national forests ])artly on the basis of expected severity of

burning conditions. Such a basis for financing helps to insure an

equitable distribution of funds.

6. An accumulation of danger ratings for different fire control units

will show legislators and those who administer fire funds the comparative financial needs of the several units reasonably similar with

respect to topography and fuel type. In Virginia, for example, there

are 103 days of class-:3 or higher danger per year (194:3-46 average).

In Massachusetts, a State with similar fuel types, there are only 65

such days. This is not the whole story, of course, but it illustrates one

useful type of information obtainable from danger ratings. Hayes,

in 1944 and 1945. and Lindenmuth, in 1946 and 1947, made exhaustive

analyses of fire records and forest fire danger for 14 Northeastern

States." They have developed strong correlations between many fire

factors and fire danger, which aid fire control executives.

There is some degree of error involved in usnig fire-danger ratings

based only on fuel moisture and weather as guides to presuppression

needs, rate of spread of fire, extent of accomplishments, and the like.

However, for areas not differing essentially m risk, visibility condi-

^'A series of processed reports issued each year for each State by the Southeastern Forest Experiment Station in cooperation with Region 7, Forest Service.

848722°—50 3
18 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

tiens, fuel type, and topography, these fire-danger ratings constitute a

basis for presuppression planning and action.

FIRE-DANGER RATINGS USED IN SUPPRESSION

Danger ratings are almost as valuable after the fire starts as before.

One of their most vital uses is to give dispatchers and fire bosses a

knowledge of fire behavior by danger classes in different fuel types.

An analysis of national forest fire reports {13) shows the following

rates of spread for hardwood leaf litter, a common fuel type.

Average spread

of fire perimeter

Fire danger: per hour (chains)

1 ^

o 12

si::::::: :::::::::::::::::::::::::::::::: lo

4 28

5 36

Thus, measurements of existing danger help to tell dispatchers whether to send 10 men or 50. Fire bosses are likewise guided in reducing

tlie manpower on a fire as danger decreases. It is reemphasized here

that other factors affecting rate of spread and resistance to control,

as well as fuel moisture and weather, must be carefully considered in

dispatching.

Fire-danger ratings are quite valuable in postfire reviews of action

taken. Without them as background, it is not possible to reconstruct

conditions accurately and conduct a critical investigation to draw

out the best lessons for strengthening future action.

DANGER RATINGS APPLIED TO DAMAGE APPRAISAL

Ratings of fire danger can be used to indicate roughly what the intensity of a fire in a given fuel type will be or has been. This information, in turn, is essential to the proper rating of fire damage, especially

in hardwood and some southern pine types. Most fire control organizations do not now have the personnel available to make a detailed

survey of each burned area and must rely on generalized tables to

ascertain damage after a fire.

The most practical way to approximate damage in a known stand

of timber is to correlate it with fire intensity as indicated by danger

measurements. In some types, trees may continue to die for five or

more years after a fire, the damage varying, of course, with fire intensity. In some instances it is desirable to begin legal proceedings

immediately to collect fire damages. Suppose a 5-year wait to determine total mortality is impossible. If so, a danger rating obtained

during the fire often serves as an index of fire intensity and consequently of expected losses. Such use has been made of ratings in the

South where a damage appraisal system has fire-danger class as one

variable (20). The average timber losses per acre in satisfactorily

stocked sapling pine-hardwood stands, for example, are as follows :

Damai/e per acre

Fire danger: hurnrd

1 Xcf/ligihlv

2 $0. 70

3 2. 20

Damage per acre

Fire (lan.^er—Continued humed

4 $4. 30

5 10.10
FOREST FIRE-DANGER MEASUREMENT 19

Such use of fire-dancer ratings is general aud should not supplant

actual appraisal of damage on the ground when such can be made.

DANGER RATING AND PRESCRIBED BURNING

Prescribed burning to reduce fuel concentrations, kill vniwanted

hardwood brush, })re[)are good seedbeds, or accomplish other things is

being practiced in certain sections on an increasing scale. An understanding of the severity of fire expected for different classes of danger

takes much of the guesswork out of prescribed burning. For example,

burning to improve game food supplies, stand composition, seedbeds,

and certain other conditions involved in the management of foi-est

resources is facilitated if probable fire intensity is known ahead of

time.

A word of caution is needed here as with other applications of danger ratings. Most prescribed fires are backfires rather tlian headfires,

and danger ratings serve merely as rough guides to fire behavior and

intensity. If the practitioner recognizes this fact and checks his information on fuel and weather conditions with experienced judgment, he

will be able to obtain the kind of burn that he planned.

Danger ratings have a place, too, in prescribed burning for protection, in that they help determine when to accomplish maximum fuel

reduction with minimum damage or risk. Hundreds of miles of

strips between parallel plowed fire lines are burned every year in the

South as firebreaks. Burning crews do a better job if their activities

can l)e guided by measured danger: and the best job is obtained with

the least undue risk.

OPERATION OF A FIRE-DANGER MEASURING

SYSTEM

The proper locations for fire-danger stations are well standardized,

as are the instruments and methods of using them. The measurements

of fuel moisture, wind, condition of vegetation, and season of year as

already outlined in this publication are herewith described in greater

detail, because the establishment and operation of an efficient firedanger measuring network require the right equipment, properly

installed and used, at acceptable locations in the forest. Experience

shows that errors of determining fire danger will be very small if the

methods described are carefully followed.

SELECTION OF FIRE-DANGER STATION LOCATION

NUMBER

The number of stations required to sample adequately the major differences in fuel moisture and weather conditions depends primarily on

elevation and aspect. In complex topography the weather is usually

quite variable, but in flat country it tends to be more uniform over large

areas. In the mountains of the East, about one station per 150,000

gross acres or one per :>00,000 acres in level or rolling country is enough

to begin with. ''Holes'' in the network wall show up if the degree

of sampling: is insufficient.
20 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Local fire occurrence is another factor to be considered. Fire-danger

measurements are more important where concentrations of fires occur.

Generally, fires occur in the valleys and accessible areas. High elevations and remote areas usually present less of a problem. The danger

stations should be located accordingly.

Finances and supervision are often practical limitations. Stations

should be established only in locations and to the extent that they can

be properly installed, adequately maintained and operated, and properly inspected and supervised. All of these measures are necessary to

produce accurate records.

Local administrative subdivisions and communication facilities also

are inñuencing factors. Good communication between the station and

the administrative headquarters is essential. Ordinarily, at least one

station is recommended for each administrative subdivision for efficient operation.

EXPOSURE

The exact spot for setting up a fire-danger station should be selected

with extreme care ; otherAvise the fuel moisture and wind measured may

be typical only of the immediate surroundings. If the site is typical

of the problem areas, however, the danger ratings obtained can be used

with certainty that they represent conditions of major importance.

All stations following the previously described systems of danger

rating should be located under natural forest conditions if satisfactory

results are to be obtained. It has been well established that soil and

air temperatures, humidity, wind, radiation, and evaporation vary

sharply between forest and open land. Thus, equilibrium fuel moistures and the rates of moisture gain and loss differ with exposure.

Also, deciduous forests go through seasonal changes, unlike nontimbered areas, that bear important relations to fuel moisture. Danger

stations cannot be operated satisfactorily in cities, on watered lawns,

or other untypical sites.

The forest conditions at a danger station site should not be modified

at any time during the course of erecting or operating the station;

litter should not be disturbed, no undergrowth should be cut, nor other

changes made. Exposures in sedgegrass fields or similar completely

exposed areas should be avoided unless a satisfactory forest exposure

is unavailable. In such a case, alternative exposures are permissible

iU).

The following points may serve as a guide to danger-station location. In the eastern mountain and Piedmont regions :

Slope.—Choose a 10- to 20-percent slope if possible ; level gi^ound to

10-percent slopes, and 20- to 30-percent slopes, are next best.

Aspect,—Choose a south to southwest exposure if possible. West

is next best, southeast and northwest slopes are permissible but not

recommended. East, northeast, and north aspects should be avoided.

Cover,—Choose a hardwood site even in a pine-hardwood mixture

where pine constitutes a good part of the stand. Moisture measurements of the important flash fuels particularly are more representative

under such conditions. Age of stand is of minor importance, but the

timber should be pole-size or larger.

In the pine areas of the Coastal Plain :

Cover.—Choose a typical pine stand representative in density and

composition of the predominant conditions. Avoid dense patches of
te'

FOREST FIRE-DANGER MEASUREMENT 21

young growth or wide, open cut-overs. The best exposure is in a

thinned pole stand or pai'tially cut saw-timber stand.

In all regions cover density and relation of topo^^raphy to prevailing

winds are more important than slo])e and aspect. Stations should be

so located as to receive winds from all directions or at least the prevailing daytime direction.

In order to maintain comparability between stations and between

administrative units, it is desii'able to have one individual designate or

approve the locations over as large an area as possible. In tliis way

all limiting factors can be unifonnly evaluated and suitable sites

chosen.

EQUIPMENT USED IN FIRE-DANGER MEASUREMENT AND

ITS INSTALLATION

A fuel-moisture scale and set of fuel-moisture indicator sticks, rain

gage, anemometer, and weighing shelter comprise the essential equipment needed at a fire-danger station. A complete list of equipment

and materials for vSetting up a station is given on page 45. The following information will be helpful in planning for such a station.

GROUND PLAN FOR DANGER STATION AS A WHOLE

The arrangement of danger-station equipment should be similar to

that shown in figure 7. Ordinarily the weighing shelter and sticks

will be at one location and the rain gage in a nearby opening.

A wire fence around the shelter and sticks is essential to reduce

the chances of stick breakage by domestic stock or wild game and

meddling by passers-by. Sometinjes a smaller wire fence around only

the sticks serves the purpose.

A definite path should be laid out for the observer to follow at all

times weithin the enclosure to avoid trampling of small vegetation and

eventual destruction of the litter. Small logs on the ground around

the sticks are recommended to avoid disturbing the litter under the

sticks.

If the location is on a hillside, a ditch may be needed on the upper

side to prevent washing.

FUEL-MOISTURE INDICATOR STICKS

The fuel-moisture indicator sticks used in the eastern and southern

United States are made from basswood. Each set consists of three

flat sticks 23/g inches by 18 inches, one-eighth inch thick. They are

exposed on w^ire supports as shown in figure 8. They should always

be 8 inches above the litter, munbered side doion. Sticks are stamped

"expose other side'- to help observers remember to return the sticks

always with the same side up. Orientation of the sticks north, south.

or in other directions is unnecessary. Sticks are carefully calibrated

at the Southeastern Forest Experiment Station, Asheville, N. C, and

can be obtained from that oflice.

Bassw^ood sticks, being flat with a maximum of surface area for their

volume, gradually lose weight because of weathering processes. During the calibration period, weatliering corrections are calculated so

that current compensations for this loss in weight can be made. A
22 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

12'

^

Gate Entrance

N

6"by 7' PostShe/ter 0

4 Woven Wire

4" to 6" Log ^^^^-^S\

partially buried — Fuel

Moisture

Sticks

SSi

W I

RAIN GAGE

Locate so that 45 degree angle from

top of gage clears all obstructions.

Figure 7.—Ground plan for danger station.

calibration card, enclosed with each set of sticks, shows the proper

settings of the sliding adjnstment on the balance arm of the scale to

allow for weathering.

When sticks are lost, broken, or chipped, a new set should be ordered at once. Old sets should be destroyed at the end of the period

indicated by the calibration card.

In hardwood stands, a location should be chosen where the sticks will

be fully exposed to the sun during the leafless season and completely
FOREST FIRE-DANGER MEASUREMENT 23

shaded during the green season. Such conditions are representative

of fuel exposures in tliese stands.

In coniferous stands, a location should be selected where the sticks

will get partial sunlight and shade through the day in a propoi'tion

approxnnate to that received by natural litter. If tlie stand is typical

in density of the type to be sampled, then a suitable stick location can

be chosen by study of probable sun and shade patterns at each of several possible spots.

F 454106

figure 8.—A set of fuel-moisture indicator sticks used in the eastern and southern

United States.

On some areas, such as cut-over land or blowdown, the sticks must

be exposed to nearly full sunlight to be typical of natural fuel. In

general, the sticks should be placed south of the weighing shelter and

free of unnatural shadow cast by fence posts, stumps, or other objects.

FUEL-MOISTURE SCALE

The fuel-moisture scale, developed by ßyram (2), is used to determine the moisture content of fuel-moisture indicator sticks. The

insti'ument (fig. 9) consists of a pivoted balance arm or beam mounted

on a lacquered 10- by 10-incli metal back. A sliding weight or

counterbalance on the beam is used to adjust the scale for sets of

sticks of different oven-dry weights from 75 to 115 grams.

The balance arm of the instrument has a small hook on the left

end to which a set of fuel-moisture indicator sticks is attached when

a reading is to be taken. The other end points to the average moisture

content of the sticks, shown on a curved scale graduated fi'om 0 to 50

percent.
24 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Figure 9.—The Appalachian fuel-moisture scale.

The biiliince arm pivots on a nickel-silver pin. All other parts

except the back are of solid brass, usually nickel plated. A standard

IDO-grani test 'weight accompanies each instrument and is used as a

ready method of leveling the device to obtain the zero setting. Each

scale is packed in a wooden box suitable for shipping. Detailed

speciñcations may be obtained from the Southeastern Forest Experiment Station, Asheville, N. C.

Tests show that when fuel moistures are below 20 percent the instrument will indicate true moistures within ±0.2 percent, while from

20 to 50 percent the error is not more than ±0.5 percent.
FOREST FIRE-DANGER MEASUREMENT 25

Current costs of the fuel-moisture scale range from $10 to $17.50

each.^

The fuel-moisture scale must be mounted substantially in a shelter

described on the following pages, so that the top edge of the instrument is about 3 inches from the roof of the box. This will give plenty

of room for the wood sticks to hang from the scale without striking

the bottom of the box.

An easy way of mounting the device, described below and illustrated

in figure 9 and later in figure 10, permits leveling it quickly and

accurately. First, screw the scale firmly to a piece of wood % by

^V2 by 18 inches long. Four holes are provided in the scale back

for this purpose. Bore a 14-inch hole near one end and cut a %- by

3-inch curved slot across the width of the board near the other end.

Then fasten the board with scale attached to a board % by 51/2 by

23 inches and secure both by means of i/4- by 2-inch carriage bolts with

wing nuts and washers as shown in figure 9.

The crosspiece holding the scale should be approximately level.

The slot will permit precise leveling of the scale before the wing nuts

are tightened. It may be leveled again if the ground settles and tips

the shelter slightly from the vertical.

WEIGHING SHELTER

A weighing shelter is necessary at a fire-danger station to protect

the fuel-moisture scales from the weather and to provide shelter from

the wind during the actual process of moisture determination. It

is also convenient to have in one shelter the wind circuit batteries,

switch, and buzzer. Other equipment such as test weight for scales,

rain-measuring stick, weathering chart for indicator sticks, wind correction chart, and instructions for danger-station operation may also

be kept there.

The weighing shelter should be a weatherproof box of the dimensions shown in figure 10. It should be mounted substantially on posts

that are set in concrete to eliminate vibration and shifting of the

shelter due to wind and settling of the ground. A full-sized hinged

door on the front of the shelter gives the observer plenty of room

in which to work. It is provided with a panel of glass, so that the

final reading on windy days may be made with the door shut. Materials for one shelter ^ can be purchased for about $15.

Figure 9 illustrates a convenient an^angement for each item housed

within the weighing shelter. Beneath the scales is fastened the

weathering correction card for wood sticks. At the right, behind the

wood sticks is a sheet showing correction for wind readings. The

large sheet in the center of the shelter gives instructions and points

(reproduced in the appendix, p. 36) that the observer must continually watch in operating a station. Buzzer, switch, and batteries are

at the right, and the test weight and can of anemometer oil are to

the left. The rain-measuring stick hangs at the side of the shelter.

Shelters should always be located on the north side of the site in

order to avoid casting shadows on the fuel-moisture indicator sticks.

If a window is provided in the door, the shelter can be turned in any

*An instrument maker who bas supplied scales in the past Is named in the

appendix.

'These materials are listed in the appendix, p. 45.

848722°—50 4
26 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

DETAILS OF WEIGHING SHELTER

SECTION AT A-A

Vg" Mosonite panel 24"x36

robbeifd m flush '/i

from edge.

-'/^"x2"bolls a »ing n

Aluminum top bent down I over sides ~

Form ^ " gutter over door -,

Hinges under ^

door slop -'

Fuel Moisture Scale

Scale adjusting board

VixS'/z" t 18"

• Scale support

^/^"x 5 '/g"x 23"

3" S elf-locking :

y

^Ooor stops

U

Side boards -

Top a bottom booro

%\7'/e'x23'/e"

feB

4' strap

hinges bolted on

8 mortised flush

^3"ángle,bolied ¿,n edge of door^.

Chain holderr^-

Double Strength Glass

13 "x 20"

Door frame /^'x I /$

Mosonite Panel

'/g",l73/^"x20"

Rabbet door frame to take

panel and glass. Waterproof

glue used on all joints

except top of door.

Mortise 3 tenon corners-^

ipf^Pipe

strop

- Vg pipe

about

49"long

- 22 ^a "

> Pipe

strop

w/Âm. Z ^J\T;J^\V

• ^1

i"*'"'!

^

'.i:l

4" X 4" X 6-10 " Posts ^

Figure 10.—Diagram of weighing shelter and details for mounting fuel-moisture

scale and anemometer.

convenient direction. If no window is provided, the shelter should

be turned so the door opens away from the prevailing winds to facilitate weighing the sticks on windy days.

The shelter should be elevated so that the numeral 10 on the graduated arc of the fuel-moisture scales is approximately at eye level of the

average observer. A step in front of the shelter can be supplied for

the special convenience of an individual if needed.

RAIN GAGES AND SUPPORTS

A rain gage consists of a sharp-edged, funnel-shaped receiver that

concentrates precipitation into a small metal measuring tube housed

in a larger metal container. The "catch" of rain is measured with a

small graduated ruler or measuring stick. The ratio of receiver area

to that of the tube is 10 to 1. Therefore, an inch of water in the tube

indicates about one-tenth inch of rain.
FOREST FIRE-DAN'GER MEASUREMENT 27

Figure 11.—The Forest Service rain gage (left) and the standard U. S. Weather

Bureau rain gage (right).

Two types of rain gages are recommended (fig. 11), the United

States AA'eatlier Bnveau standard pattern and the Forest Service type.

The former is ruggedly constrncted of sheet metal, is about 28 to oO

inches high and 8 inclies in diameter, and has a capacit}' of 2 inches

in the measuring tube and hirge overflow cai^acity. Its cost ranges

from about $8.50 to $25.

Most danger stations use the Forest Service rain gage, costing $2.50

to $5. It is made of galvanized iron and is about 12 inches high and

slightly less than 8 inches in diameter. It has a capacity of i/o inch

Figure 12.—The Forest Service rain gage and post mounting.
28 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

plus a 6-inch overflow. In other respects its resembles the larger

gage. Comparative tests conducted by the Northern Rocky Mountain Forest and Range Experiment Station and by the Southeastern

Station indicate that the Forest Service pattern is satisfactory.

Rain-measuring sticks are graduated rulers reading to inches,

tenths, and hundredths. Broken

or dirty sticks may be replaced at

a cost of 15 to 30 cents per stick.«

Rain gages should be securely

supported so that the funnel top

is level and about waist high. A

Forest Service gage can be supported, as shown in figure 12, atop

an 8-inch post to which four vertical strips have been nailed. At

permanent weather stations, a

support such as the one diagrammed in figure 1-) is desirable.

The rain gage should be placed

in an opening in the forest or a

nearby clearing where a 45° angle

from the top of the gage clears

the nearest obstacle. This puts

the rain gage at a distance at least

equal to the height of the obstacle.

Sometimes such an exposure is not

possible but it should be selected

when available. Next best is to

place the gage directly under the

center of the largest crown

opening.

- Top of post

must be level.

^ '\Post and uprights

P to be plumb.

_ f^' Slob sides to receive

y uprights and to get

L/^ required spacing exact.

^-5

Post 9'/¿"to 10"

(natural peeled)

-Ground line

-i^ Treat surface exposed

to earth.

Figure 13.—Diagram of rain-gage

support.

ANEMOMETERS

There are a variety of low-cost cup anemometers satisfactory for

use at fire-danger stations. These are all the so-called "airways" or

"buzzer type" that indicate current velocity by transmitting signals or

buzzes for each %o ii^ü^ ^f wind passing the instrument. Several

anemometers are shown in figure 14.

Some types are more accurate than others, especially atlow velocities,

but all can be recommended for danger measurement.^ All of these

anemometers use correction charts to convert indicated to true velocity.

Anemometers do not come equipped with a mounting device, but

most of them have bases threaded to fit a standard %-inch or i/^-inch

pipe thread. A suitable iron pipe mounting is diagrammed in figure

10. All wire, batteries, buzzers, and switches necessary to complete

the signal circuit can be purchased at any hardware store. Two

li/^-volt dry-cell batteries will supply the necessary current. A small

* Manufacturers supplying rain gages and measuring sticks are listed in

the appendix.

^ Instruments may be obtained from the manufacturers listed in the Appendix;

prices range from $17.50 to $35 per instrument.
FOREST FIRE-DANGER MEASUREMENT 29

electric buzzei' or (lasher bulb iirovides tlie best signal and a singlebladed knife switcli is reconnnended.

The anemometer shonld be supi)orted so that tJie cu])s are at or

within half a foot of the 8-foo( level, a height adopted as standai'd for

ground wind measurement at eastern (ire-danger stations. No artificial

barriers to wind movement, such as buildings, should modify typical

forest conditions in any direction. Anemomelers should not Í)e nearer

than 10 feet to trees 10 inches or larger in diameter.

f

^m^%m%^^

u

Figure 14.—Number 1 is a highly accurate and expensive anemometer used at

Weather Bureau stations. Numbers 2 to 5 are low-cost anemometers satisfactory

for use at fire-danger stations. Number 2, Chisholm; 3, Friez airways type; 4,

Stewart; 5, Dozier.

Occasionally a satisfactory anemometer exposure caunot be found in

tlie immediate vicinity of the danger station, on account of the interference of topography or buildings. If so. the anemometer may be set

up in a desirable S|)ot to get a better exposure. By wiring the instrument back to the weighing shelter and atlding suflicient batteries, wind

readings may be taken without the necessity of the observer walking

tc the chosen spot.

Although the %(,-mile transmitters are satisfactory for fire-danger

measurement, there is some advantage in having cumulated wind

movement, because a more reliable average can then be obtained.

Several types of counters or mileage cumulators are available foi' attachment to anemometers. Also, standard anenujmeters of high

(juality, with dials from which total wind movement to the nearest Vi»

mile can be read, may be purchased from several companies for prices

starting at $80. Instruments can also be obtained with the additional

Yeo-mile transmitting feature.

WHEN TO MEASURE WEATHER AND FUEL FACTORS

The man responsible for fire control uses fire-danger measurements

to help him answer two basic questions: What is the likelihood of fires

starting'^ And how big is the job of suppressing any fires that do occur^ All other questions are subordinate. Accordingly, fire-danger
30 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

measurements should be taken at times which will provide the best

answers to those two basic questions.

The number of accidental fires which start is determined principally

by the prevalence of debris-burning fires, campfires. discarded matches

and smoking materials, hot coals, etc., and the inflammability of the

forest fuels. The size of the suppression job for a sinale fire is also

determined principally by the inflammability of the fuels and wind

velocity. Topography, ground cover, and many other factors contribute, but to a lesser degree.

An analysis of daily fire occurrence in the Northeast, based on 10,000

fires which occurred in 12 Northeastern States from October 1942

through June 1943,. shows that almost half of the fires start between

noon and 3 : 30 p. m., e. s. t. A summary of dew-point temperatures at

Asheville, N. C, (18) for the years 1926-32, shows that on the average

the minimum dew-point temperature on clear and partly cloudy days

falls to a practical minimum near noon, and thereafter drops slowly

to an absolute minimum near 3 p. m. Dew point is a direct index of

the amount of moisture in the air. A summary of mean relative

humidity and maximum air temperatures recorded at Burlington,

Vt., (r5J July 1911 to December 1915, inclusive, shows that on the

average minimum relative humidity values and maximum air temperatures occur between 2 p. m. and 3 p. m.

Limited records of fuel moistures indicated by sticks in eastern

Virginia show that minimum moisture content, 3 or more days after

a rain of 0.25 inch or more, occurred at 3 p. m., e. s. t., on approximately

75 percent of such days. This apparently indicates a slight lag in

time for the sticks to come to equilibrium with the factors controlling

their moisture content. Generally speaking, the average daily march

of wind velocity follows closely the changes in temperature and is in

direct proportion to the temperature over level regions or at low elevations such as valley floors or lower slopes. Some seasonal variations do

occur in the mean values of these factors but are ignored for practical

purposes.

All this evidence indicates that in the East the answer to the two

basic questions can best be determined between 1 p. m. and 3 p. m.,

e. s. t. The 2 p. m. observation made by most agencies is probably a

good compromise and is reconnnended as the basic observation. It

should be made at a minimum of one station on each administrative

unit on ever}^ day of the year to provide adequate records.

Some additional observations are required by the United States

Weather Bureau for forecasting ]>urposes. These should be made as

directed and are not covered by this discussion, which refers particularly to fire control.

Early morning observations have little value in fire control in

the eastern United States. Indicated fuel moistures are generally

high and are influenced mainly by conditions that prevailed during

the night. Wind velocities generally are low, in keeping with the

temperature. Conditions recorded at danger stations in the early

morning do not set a pattern for the day. Early morning observations

are not recommended. On the other hand, late morning observations

have been found useful to determine when a lookout should actually

be "on top," as opposed to cutting wood, packing water, or doing other

work on the ground. They are also useful to indicate the pattern of

weather to be expected later in the day.
FOREST FIRE-DANGER MEASUREMENT 31

Late afternoon observations at 5 j). ni. normally show a decline

from the peak dan<i-er earlier in the day. Usually by late afternoon

fuel moisture has increased and wind velocity has fallen. Occasionally

a continuation of hi^ih danger into the evening hours is possible.

Hence, a 5 p. m. measurement durin<>' the lire season is recommendínl.

In the nonhre season, however, year-long stations should make the

2 p. m. observation only.

Additional observations to control the action on going iii"es, of

course, should be made as needed. These extra observations need not

be part of the permanent record.

TAKING MEASUREMENTS AND RATING FIRE DANGER

Taking iire-danger measurements and integrating them into numerical ratings require a high degree of accuracy if the ratings are to be

a reliable basis for fire control action. Carefully developed instructions for observers are given in detail in the Appendix to ensure

proper measurements.

The numerical ratings are obtained from the danger meter by

following instructions printed thereon. It should be remembered

that the class of fire danger or burning index obtained represents

conditions at the particular time and place the ol)servations were

made. Dispatchers or others who use danger ratings Avill get the

most help from the ratings if they are thorouglily familiar with the

fire weather pattern over their district in relation to measured fire

danger. By watching fire behavior in relation to topography, fuel

type, and wdnd direction, they will learn how to interpret and modify

danger ratings for each sl()])e or drainage. For example, some coves

tend to remain w^etter than others. Fuels on ex})osed ridge tops may

dry out quicker after a rain and reach lower minima than the dangerstation ratings indicate. Exi)erienced judgment is invaluable in

applying the basic burning index values in the job of dispatching.

SUMMARIZING FIRE-DANGER RECORDS

Administrative units usually require ratings of fire danger for

daily fire control planning. When only one fire-danger station is

operating within a unit, the ratings are used to represent the entire

area. When one unit has two or more danger stations, however, some

method of calculating average unit danger is needed.

One method of summarizing, formerly quite popular, consisted of

averaging the fuel moisture, wind, and rain data from the several

stations. This often gave ambiguous results and is no longer in general use. By averaging the rain, the unit as a whole was often basing

its ratings on a much smaller amount of precipitation than some individual stations actually received.

Another method of summarizing, used by the Southeastern Forest

Experiment Station and now incorporated in the scale of the new type

5-\V fire-danger meter, is that of averaging weighted danger ratings

from all the individual stations in the unit to determine a single rating

representing the entire unit. Danger ratings expressed only in the

five classes cannot be aA^eraged arithmetically without weighting. This

is true because a class-4 day is not four times as severe a day as a
32 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

class-1 day so far as fire occurrence, rate of spread, or any of the other

elements of fire control are concerned. The class-4 day actually is

many times more severe. Accordingly, the scale on the type 5-W

meter was developed to express this comparison of severity in a linear

form based only on the element of fire occurrence. Kecords from

thirteen Northeastern States comprise the basic data.

Any number of ratings on the type 5-W meter scale can be averaged

arithmetically to determine a composite average representing the

group, provided the areas represented by the individual ratings are

approximately equal. Similarly, danger ratings expressed in the

five-class scale when converted to the type 5-W scale by means of the

tabuUition on page 9 can be averaged in the same manner.

This method may be amplified by including area weight factors

where the areas represented by different stations differ significantly.

For example, a district is served by danger stations A and B. A represents one-third of the district and has a danger rating of class 2 or

a burning index of 5 today. B represents two-thirds of the district

and has a danger rating of class 3 or a burning index of 20 today.

The district rating would be calculated by multiplying each area by

its corresponding burning index and adding, as follows:

Area A: % X r»= 1.07

Area B: % X 20=13. 33

District average (sum) 15.00 (or class 3).

Tables or alinement charts can easily be developed to handle the

mathematics of this method, tliereby making it very simple to apply

in actual practice. This method is recommnded in the mountains of

the eastern United States. Until a 100-point scale is developed for the

Coastal Plain meter, danger classes should not be added and averaged

atthe Coastal Plain and Piedmont stations.

PREDICTING TOMORROW'S FIRE DANGER

Like any other kind of forecasting, the prediction of fire danger

requires judgment. It cannot be accomplished mechanically. Fuel

moisture and wind velocity are particularly difficult to forecast. Even

the well-known weather factors like air temperature, humidity, and

precipitation cannot be predicted for small localities with a high

degree of accuracy.

Regular fire-weather forecasts are very useful, and they attempt

with considerable success to localize predictions for national forests

or similar-sized units. Further localization depends on local laiowledge and interpretation gained from on-the-ground experience.

In the eastern United States, fire-weather forecasts are prepared

by the United States Weather Bureau and originate from their Asheville, N. C, and Boston, Mass., offices. Special fire-weather forecasters are employed at both points. Forecasts are available to all

interested parties in the territories served during regular designated

seasons and also by special request.

Regular weather forecasts generally include information on clouds,

relative humidity, temperature, wind velocity, wind direction, precipitation, and factors affecting visibility. Recently fuel-moisture

predictions have been included on a trial basis. Instruction booklets
FOREST FIRE-DANCER MEASUREMENT 33

furnished free of charge hy eil her (jñice fully explain all codes and

the terminolooy used {Jo) and must be studied prior to making any

attempt to use these forecasts.

Regular within-seasou forecasts are not made for any particular

point but rather cover an area of varying size within whicli the variables considered are expected to be fairly uniform. Experience and

study will help an observer to interpret the forecasts specifically to

fit local conditions. Requested forecasts, on the other hand, attempt

to cover the specific designated area.

Predicted wiud velocity is expressed in terms of in-the-woods velocity, 8 feet above ground. In tlie absence of specific forecasts of fuel

moisture, this factor nuist be calculated locally from the air temperature and relative humidity ])i'edictions. The following general rules

are helpful in nuiking calculations :

1. Rising temperature, no change in relative humidity : somewhat

lower fuel moisture.

2. Rising temperature, higher relative humidity: little change

in fuel moisture.

3. Rising temperature, lower relative humidity: mucli lower fuel

moisture.

4. Lower temperature, no change in relative humidity : somewhat

higher fuel moisture.

5. Lower temperature, higher relative humidity : nuich higher fuel

moisture.

6. Lower temperature, lower relative humidity: little change in

fuel moisture.

Sufficient time must have elapsed following a rain to permit the

indicator sticks to come to equilibrium with their surroundings before

these general rules apply. This })eriod varies with the season. By

local study and observation, these rules can be expressed in actual

values with reasonable accurac}^, thereby facilitating their use.

The meter for the Piedmont and Coastal Plain has a fire-danger

forecasting feature incorporated in it. If a prediction foi* tomorrow's

weather is available, the meter may be used as a guide to coming fire

danger. Howevei', connnon sense and a careful study of existing and

predicted weather are often more satisfactory than any mechanical

method.

TRAINING AND INSPECTION

Emphasis must continually be placed upon accuracy to obtain reliable records. An adequate program of training and inspection is

indispensal)le in accomplishing this objective.

Ordinarily a qualified trainer can profitably spend at least 2 hours

with each new observer at the station, going over the details pertinent

to reading the various instruments and recording the data. Followup training needs will vary Avith observers and can best be determined

by periodic inspections and checking of the records.

Inspections as frequent as monthly are desira])le, but a minimum

of two per year, spring and fall, are'essential. The jobs of locating

stations, training observers and dispatchers, maintaining and servicing the instruments, checking and filing records, assemblhig and

analyzing data for most effective use, etc., can all be handled efficiently

848722°—50 5
34 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

by one man to provide proper coordination. Proper attention to these

functions will require the full-time services of 1 man for approximately each 100 danger stations in continuous operation.

A standard inspection outline or check list is helpfulto assure proper

attention to details. A su^igested outline, used successfully in the

Northeastern States since 1045, is inchided in tlie appendix.

LITERATURE CITED

(1) BiCKFORD, C. A., and BRUCE, DAVID.

1939. A TENTATIVE FIRE DANGER METER FOR THE EONGEEAE-SLASH PINE TYPE.

South. Forest Expt. Sta. Occas. Paper 87, 7 pp. [Processed.]

(2) BYRAM, GEORGE M.

1940. THE APPALACHTAN FUEL MOISTURE SCALE. .Joiu*. Forestry 38: 493-

49.5, illiis.

(3) and .7 EM ! SON, GEORGE M.

1943. SOI AR RADIATION AND FOREST FUEE MOISTURE. .Tour. AgT. ReS. 67:

149-17f), illus.

(4) — and JEMISON, GEORGE M.

1948. SOME PRINCIPLES OK VISIBILITY AND THEIR APPLICATION TO FOREST FIRE

DETECTION. U. S. Dept. AsuY. Tecli. Bnl. 9r)4, 61 pp., ülus.

(.5) DAY, PRESTON C.

1917. RELATIMî HXTMIDITIES AND VAPOR PRESSURES OVER THE UNITED STATES,

INCLUDING A DISCUSSION OF DATA FROM RECORDING HAIR HYGROMETERS. Monthly Weather Rev., Sup. 6, 61 pp., illus.

(6) GiSBORNE, H. T.

1928. MEASURING FOREST-FIKE DANiiER IX NORTHP^RN IDAHO. U. S. Dept.

Agr. Misc. Pnb. 29, 64 pp., illus.

(7)

(8)

1936. MEASURING FIRE WEATHER AND FOREST INFLAMMABILITY. Ü. S. Dept.

Agr. Cir. 398, m pp , jn^i^.

1936. THE PRINCIPLES OF MEASI'RING FOREST FIRE DANGER. JoiU". Forestry

34: 786-793, illus.

(9) HOFMANN, .T. v., and OSBORNE, W. B., JR.

1923. RELATIVE HUMIDITY AND FOREST FIRES. U. S. Dept. Agr., Forest

Serv., 12 pp., illus.

(10) .1 EM I SON, GEORGE M.

1935. INFLUENCE OK WEATHER FACTORS ON MOISTURE CONTENT OF IJGHT

FUELS IN FORESTS OF THE NORTHERN ROCKY MOITNTAINS. Jour. AgT.

Res. 51: 88.5-906, illus.

(11)

1942. THE MEASURE^rENT OF FOREST FIRE DANGER IN THE EASTERN UNITED

STATES AND ITS APPLICATION IN FIRE PRE\TCNTION AND CONTROL.

Appalachian [Southeast.] Forest Rxpt. Sta. Tech. Note 50, 59

pp., illus.

(12)

1944. FOREST FIRE DANGER INDEXES. .TouT. Forestry 42: 261-263, illus.

(13) and KEETCH, .TOHN J.

1942. RATE OF SPRKAD OF FIRE AND ITS RESISTANCE TO CONTROL IN THE FUEL

TYPES OF EASTERN MOUNTAIN FORESTS. Appalachian [Southeast.]

Forest Expt. Sta. Tech. Note 52, 15 pp., illns. [Processed.]

(14) LINDENMUTH, A. W., .IR., and KEETCH, J. J.

1949. OPEN METHOD FOR MEASURING FIRE DANGER IN HARDWOOD FORESTS.

Southeast. Forest Expt. Sta. Tech. Note 71, 11 pp., illns.

[Processed.]

(15) MCCARTHY, E. F.

1927. WEATHER AND FOREST INFLAMMABIIJTY IN THE SOUTHERN APPALACHIANS. U. S. Monthly Weather Rev. 55: 119-122, illus.

(16) MITCHELL, J. A.

1929. FOREST FIRE HAZARD AS AFFECTED BY WEATHER CONDITIONS, FOREST

TYPI-:, ANT) DENSITY OF COVER.. UELíV. Wiscousin Agr. Expt. Sta Res

Bui. 91, 26 pp., illus.
FOREST FIRE-DANGER MEASUREMENT 35

(17) MuNNS, E. N.

1921. EVAPORATION AND FOREST FIRES. U. S. Moiithlv Weather Rev 49-

149-ir»l>, illiis.

(18) I'lEKCK. LELAND T.

1934. niruiVAi. VARIATION IN THE DEW-POINT IKMI'EKATUKK AT ASHEVILLE,

N. (\ U. S. Moiilhly Weather Rev. 62 : 2.S9-298, illus.

(19) SHOW, S. H., îUKI KOTOK, I^]. I.

liVJi"). wEATirKi: coNDrnoNs AND FOREST KIKES IN CAEIEOKNIA. U. S. Dept.

Aixv. I>oi)l. (Mr. or)4, 24 m)., illns.

(20) SOX^THEKN STAIIIS FOKKST F IKE CONTROL CHIEFS' F0RE8T FiRE DAMAííE

COMMITTEE, in fooperntioii with the U. S. FOREST SKHVICE.

1949. SOUTHERN STATIÙS FOREST FIRE DAMAGE TABLES AND PROCEDURES. 9

pp. (Re.iAToii 8, U. S. Forest Service, Atlanta, Ga.) |Process«Ml. |

(21) STICKEL, FAUL W.

19,S1. THE .\IEASl'KEMi':.\'|' AM) KXTlOKI'ia^rrAT ION OF FOREST EIHE-Wl'lAITI KU

IN THE WESTEKN ADIKONDACKs. N. Y. Stat(^ College of Forestry,

S.M-acuse Fiiiv. Tech. riih. ;;4, ll.") pp., illus.

(22) UNITED STATES I'^OKEST SEKVICI'>.

1939. C4L0SSARY OF TI:RMS USED L\ FOREST FIRE CONTROL. 24 pp.

(23) UNITED STATES WEATHER BUREAU.

1948. FIRE WEATHER KOKECAST TI:RMINOLO(;Y. 8 pp. [Processed.]

(24) WiLKiNs, AUSTIN H.

1948. THE STORY OF THE MAINE FOREST FIRE DISASTER. Jolir. FoiVStry 4H :

568-573.

APPENDIX

INSTRUCTIONS FOR OBSERVERS AT FIRE-DANGER

STATIONS

The usefulness of fire-danoer ratings depends upon the reliability

of the records that go into the ratings. Fire-danger station observers

should realize that their accuracy and carefulness, above all else, are

absolutely essential if the most is to be obtained from a system of

danger measurement. î'igure 15 gives instructions and points that

the observer must continually watch. Each observer should understand that the errors he makes carry right on througli to presupjn'ession and sui)])ressi()n action. He can be responsible for a fire getting

av^a}' if he is careless in lia lulling and reading instruments.

CARE OF INSTRUMENTS

Proper care of instruments is essential to obtaining reliable firedanger records. Many of the following points can be handled by the

observer. Othei's slionld be handled by an administrative officer.

Definite responsibilities for the various jobs should be established by

the organization involved.

Fuel-mohtiire incUcator sticks.—Always be sure that the three sticks

which constitute a set are kept on the'^wire supports with the side

marked "expose other side" down, approximately horizontal, and 8

inches above i\\^ litter as shown in figure 8. They should always be

returned to this position immediately after each weighing and left

exposed to the weather at all times, even when the stat'wv is not heing

operated. The many sets of wood sticks in use will not weather uniformly if one set is exposed one way and a second set in anotlieimanner.
36 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

INSTRUCTIONS FOR ?1RE ElAMGER STATION OBSERVERS

(Post this sheet in weighing shelter)

GEî'TSRAL;

Accuracy of all readings is essential. i:e-q-er guess at a value. .7rite

reading down as soon as taken,

FUEL I.:0ISTUR5 I/IEASUREIvENTi

1. Instructions for new sticks: (a) The date when new sticks are first

exposed and each date when a weathering correction is to be rade should be recorded on the weathering correction card as soon as the sticks are placed out

in the weather; (b ) new sticks can be used 6 to 8 months; (c) destroy old sticks

v/hen new ones are put in use.

2. Scale should read exactly 0 percent when the lOO-gran test weight is

on the hook and the counterbalance slide is set at 100.0 grams. Check this

weekly. If not reading 0, correct by loosening wing nuts and tilting scale

up or down.

3. Before weighing sticks be sure that the counterbalance slide on the

horizontal beam is set correctly at the point indicated on the weathering correction card.

4. V/eigh all 3 sticks together, ^o not read the scale until the pointer

has become still. Alv/ays tap the pivot block with finger or pencil just before

reading to avoid possible error from friction in the pivot.

5. Handle wood sticks with care — never with sv/eaty, dirty, or greasy

hands — avoid splitting, chipping, or marring — brush off lightly with a

clean, dry clotli any dirt that gets on sticks,

6. After weighing always replace sticks on their supports with the numbered side down. Maintain adequate litter under sticks at all times.

7. If fuel moisture scale becomes sluggish, place a fevj- drops of kerosene oil on the pivot — never use machine oil.

\7IND ]/EASURSI.Œ:NT :

1. To measure wind: (a) close switch; (b) listen for first signal;

(c) immediately at the end of the first signal, start timing for a 2-minute

period; (d) count all signals that occur for exactly 2 minutes; (e ) refer to

wind correction.chart to determine true wind velocity. If no signals occur,

the vdnd velocity is 0.

2. Oil anemometer once a month — use only 2 or 3 drops of a very light

oil, such as typewriter oil or 3-in-l.

RAIN MBASUREIVGNT :

1. Rain is measured as follows: (a) remove funnel top of rain gage;

(b ) lower rain measuring stick doT.vn inside measuring tube until the stick

rests on the bottom; (c) raise rain stick and read the top edge of the water

line (The rain stick is marked off in hundredths of an inch and should be read

to the nearest hundredth.); (d) overflow that collects in the large can should

be poured into the measuring tube, measured, and added togetJier to get the

total rainfall,

2. If snov/ is expected, remove funnel top and measuring txjbe, and let

snow collect in large container. To measure, melt the snow, pour water into

measuring tube and proceed as in measuring rain.

3. Always remove inner tub© when there is danger of freezing weather.

Figure 15.—Instruction sheet to be placed in weighing shelter.

If the spot where the sticks are placed is exposed to high winds, it

may be necessary to secure tliem to the wire supports to prevent them

from being blown off. This may be done by using a piece of heavy

galvanized wire hinged to one support so that it rests across the sticks

and can be swung out of the way when a reading is to be taken. Or

a "croquet wicket" made with right angle bends can be placed over

the three sticks to hold them with moderate pressure to the wire

supi:)orts.
FOREST FIRE-DANGER MEASUREMENT 37

The fuel-moisture indicator sticks will ^ive a reliable indication of

the chanoes in fuel moisture content if they ai'e handled carefully and

the following points observed :

1. Never handle the sticks with sweaty, dirty, or ^^l'easy hands.

Excessive handling clogs the pores of the wood so that it will not

respond readily to atmos[)heric moisture changes.

2. Handle the sticks carefully to avoid s])litting, chipping, or

marring.

0. If dust or dirt of any kind should get on the sticks, brush it oft*

lightly with a clean, dry cloth or soft brush.

4. Keep the ground under and around the wire supports covered

with leaves so that hard rains will not splash mud on the sticks.

5. Notify the ranger or other responsible forest officer if anything

happens to the set of sticks, so that inunediate replacements may be

made.

The removal of wood fibers from the surface of the sticks by wasps

or other insects can usually be ignored. Ordinarily the thickness of

the layer removed is less than that of a piece of paper and only a

portion of the total surface is affected. The resulting error under

such conditions is slight.

Weighing shelter.—The following check list is helpful in maintaining the shelter in first-class condition :

1. Keep posts steady and plumb; they should be set in concrete

or braced.

2. Keep box firmly fastened to posts.

3. Maintain box free of leaks and cracks.

4. Hang door properly so it closes tightly.

5. Give shelter a coat of pa i ut once a year.

Fuel-moisture scale.—The fuel-moisture scale should be handled

with care the same as any other delicate instrument. Observance of

the following points will help produce accurate records.

1. Do not oil the pivot. This is made of hard nickel silver, and requires no lubricant.

2. When removing sticks from hook, avoid jarring the beam.

3. Be sure hook is hung properly and swings freely in all positions.

Usually the hook is shaped with a small half circle ou one end: this

is the part on which the sticks are hung. The other end of the hook

is a flat arm which is the end that goes through the beam. If the hook

becomes rusty or lost, replace with one of similar shape. A common

paper clip provides suitable wire for this use.

4. If the shelter or scales are to be moved, tie the scale beam to the

stop pin to prevent jarring.

5. If the bright parts of the scale become corroded, clean with kerosene or a nonabrasive metal polish.

Anemometer.—RegiúñT attention to this instrument is required to

assure proper service and accuracy. The following points should be

observed :

1. Check lubrication once each month. If oil is needed, add only two

or three drops of a light or low viscosity household oil or typewriter

oil. Less oil is needed in the summertime. Excessive oilmg is harmful as it gums the instrument and makes it sluggish.
38 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

2. Keep the spindle plumb at all times. Otherwise, uneven wearing

will result and inaccuracies will occur.

3. Cups should be attached tightly to the arms. If loose, replace

entire rotor assembly. • • i

4. Check the circuit switch periodically to be sure it is tight and

clean. If loose, the rivet and prongs can be tightened by mashing with

a pair of pliers. If corroded, the prongs and blade can be cleaned

with fine sandpaper or by scraping with the blade of a knife.

5. If buzzer fails, check contact points, as this is the usual cause of

trouble. If points are stuck together, break apart and clean points

with fine sandpaper.

6. Keep all connections tight at all times.

7. Anemometers should be taken down and carefully cleaned once

a year. Instructions for cleaning each type of instrument are given

on pages 47 to 50. Observers should not take these instruments apart

for cleaning unless they have been specifically instructed to do so by

their superior officer.

Eai7i ga(/e,—The following points all influence the reliability of the

rainfall records:

1. Keep top of gage level.

2. Plandle funnel carefully; if it becomes bent, restore its round

shape.

3. Check currently for leaks ; resolder any which occur.

4. Handle stick at top only, so lower part will not become greasy.

If it becomes illegible, replace with a new one.

5. Remove inner tube during freezing weather to prevent damage. At intermittently operated stations, always remove

inner tube when leaving station.

6. For greater accuracy in regions where snow occurs, remove funnel during Avinter to catch snow.

7. Clean out debris currently.

HOW TO MEASURE WEATHER AND FUEL FACTORS

Moishire content.—The fuel moisture is determined at each observation at the assigned time except when the ground is blanketed with

snow. Under such conditions the sticks are not weighed and the snow

on the sticks is not disturbed. The snow is allowed to melt in a

normal manner until weighing of the sticks is resumed. The observer should follow the steps given below when determining fuel

moisture.

1. Check the fuel-moisture scale to see that it is level or that its

"zero setting" is correct. To do this, first set the sliding adjustment

on the balance arm at 100 and hang the 100-gram test weight on the

hook at the left end of the beam. Wlien the beam stops swinging,

tap the pivot loith the ßnger to settle the pointer to the correct mark.

It may lag a little owing to a slight amount of friction at the pivot

point. If the pointer does not read zero, loosen the wing nut on the

right and move the slotted scale support until zero is indicated. After

the wing nut is tightened, tap the pivot with the finger again. If the

pointer still does not read zero, repeat the operation until the zero

point is reached. The scale should thus he checked and leveled once

each week or whenever it may get out of adjustment for any reason.
FOREST FIRE-DANGER MEASUREMENT 39

2. Adjust the slider on the beam by setting it exactly on the figure

corresponding to the corrected weiglit of the sticks. Tlie corrected

weight is shown by calendar date on the card which accompanies each

set of sticks (fig. 1()). This corrected weight is changed periodically

because the sticks lose a slight amount of weight when exposed to the

weather.

WEATHERING C0RHECTI013 CARD SET W. ^8 -S3V

Set slider on "balance arm of scale according to date

Calendar Date Scale Setting

First Exposed QcJc^ /, /^ ^/ 9? .<^

6 weeks later ¿Zoc^y /¿h^/^^S' f/. 9"

6 weeks later jzLe^ cZS^/q^^S //. ^

I!^TRUGT ions

When the sticks are first exposed, the three dates

should "be entered in the blank spaces above, using

a calendar. Use slider setting recorded on top line

for first 6 weeks, middle line for second* 6 weeks,

and "bottom line for remainder of the 6-!nonth period.

Figure 16.—A sample weathering card.

All the information on the card except the dates is ñlled in before

the sticks are mailed. The obsei'ver must nil in the dates as indicated,

using a calendar. Post the card in the shelter beneath the scales for

handy reference. In case the card is lost, do not request a new set of

sticks. A replacement card can be obtained just as cjuickly from the

Southeastern Forest Experiment Station by supplying the number and

its original weight which are recorded with indelible pencil on the

underside of each stick.

0. Hang the three wood sticks together on the scale hook by means

of the hanger fastened to each &i:ick. Figure 9 illustrates the correct

manner in which to suspend the sticks on the hook. After the beam

stops svnnging^ tap the pivot before reading the scale. This is important and its omission has caused frequent errors in the past. The

pointer indicates the average moisture content of the three sticks.

This should be read to the nearest one-tenth of 1 percent up to 20 percent and nearest one-half of 1 percent above 20 percent.

4. Record the fuel moisture as read. Whenever the ground is

blanketed with snow, record "S^' (for snow) in the fuel moisture column of the daily record form.

Wind velocity.—Wind velocity is determined at each observation at

the assigned time except when the ground is blanketed with snow or

the fuel moisture exceeds 30 percent. Wind measurements are made

as follows :

1. At stations equipped with a buzzer-type anemometer, close the

switch and listen for the first buzz. Start timing with a watch immediately after the first buzz stops. Do not count this first signal but
40 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

count all others during the ])eriod indicated on the wind correction

chart posted in the shelter. Whenever the wind is variable or gusty,

take a second separate observation and average the velocity from the

two observations or double the length of the first observation period

and divide the number of signals by two.

If a station is equipped with the Weather Bureau type anemometer

having a dial, average velocity is obtained by subtracting one dial

reading from a second, later one. To get miles per hour, this ditierence which represents the total air movement for the period must

then be divided by the number of hours between the two readings.

For example, at 1 p. m. a reading of 621.5 was observed and at 5 p. m.,

640.7. The difference is 19.2 miles, which divided by 4 hours equals

4.8 miles per hour average velocity. This value must then be corrected, as explained in the next point. Observers should note that the

dial on this type of instrument goes up to 990.0 miles and then starts

over again.

2. Î or buzzer-type anemometers, refer to the wind correction chart

posted in the shelter. Opposite the number of signals counted for the

established period, read the actual wind velocity directly. For example, with a Stewart anemometer nine signals in 2 minutes equal an

actual velocity of 5.5 miles per hour.

For the Weather Bureau dial type anemometer, refer to the correction chart in the column for your special anemometer as described.

Opposite the group within which your average falls, read the correction which must be added or subtracted to obtain the actual velocity.

For example, an average of 4.8 m. p. h. with a three-cup anemometer

requires an addition of a cor^pction of 1 m. p. h. Therefore, actual

velocity would be 5.8 m. p. h.

3. Record the actual velocity to the nearest one-half mile. If cups

are not turning, record as zero. If the ground is blanketed with snow

or the fuel moisture exceeds 30 percent, record "X" (for no observation

taken). Correction charts for anemometers are given on pages 51

to 58.

Precipitation,—Precipitation is measured each day, usually once

during the 24-hour period either at the first or last observation for the

day. The administrative agency should establish a standard procedure

for this observation. Precipitation is measured as follows :

1. Carefully remove the funnel from the top of the gage. If the

small measuring tube is level full, empty it and refill it from the contents of the larger can. Count the number of level full tubes thus discarded. Wlien the small measuring tube is not level full, measure its

contents with the graduated stick furnished for this purpose. Handle

only the end of the stick with the highest graduations, to prevent the

stick from becoming illegible from grease or dirt. Insert the ox^posite

end of the stick into the measuring tube, which is either standing level

inside the main can or has been placed on a chosen level surface. Hold

the stick vertical and avoid stirring or splashing. Withdraw the

stick and note the position of the water line with respect to the

nearest graduation.

2. Sticks are graduated in inches, tenths, and hundredths of rain.

An inch of water equals only one-tenth inch of rain because the funnel

top of the gage concentrates ten times the actual rainfall into the measuring tube. The amount of rain is recorded in decimals, like dollars
FOREST FIRE-DANGER MEASUREMENT 41

and cents: 1.25 equals 1 incli and 25 hundredths. Each level fidl

measuring tube will be counted as i/> inch if the shorter, galvanized,

Forest Service type gage is used, or 2 inches if the taller, copper,

AVeather Bureau gage is US(M1. It is true that allowing full ci'edit for

each such tubeful without inserting the stick causes a slight error equal

to the volume of the stick. But such error is slight enough to be

negligible.

3. Record actual reading in inches and hundredths. If amount is

less than one-half of one-hundredth (less than halfway of the first

graduation on the stick), record a "T" for trace. If only a few drops

of rain have fallen and are not noticeable in the gage, also record a

"T." Do not record moisture from dew or condensation. Record

precipitation each day even though fuel moisture and wind observations may have been omitted according to instructions. In regions

where snow is likely to fall at intervals through a winter fire season,

the funnel top of the rain gage should be left off to facilitate the catch

of snow.. Always melt snow and ice in the rain gage and pour the

water into the small inner tube before measuring in the regular way.

Days sin^^e last rain.—For the mountain regions, all rains with a

total precipitation of less than 0.25 inch are disregarded when tallying

"days since last rain." For the Piedmont and Coastal Plain, where

meter type 7 is used, all rains less than 0.50 inch ai-e disregarded. To

determine total precipitation, add together all precipitation measured

over a period during which measured fuel moisture does not drop

below 20 percent. For example, suppose it rained 0.38 inch yesterday

afternoon and 0.20 inch this morning, stopping at 11 a. m. when it

cleared and the sun came out. Since no ])i'onounced drying could have

occurred during the night between the two rains, for all practical

purposes the amount of the last rain would be 0.58 inch. If "today*'

had remained cloudy and foggy and the fuel moisture did not drop

below 20 percent, zero days since rain would be shown for today.

AVhen intermittent showers extend over a period of a day or more with

the fuel moisture remaining above 20 percent, they should be called

one rain.

It is emphasized that all distinctly separate small rains and showers

(separated by conditions of fuel moisture below 20 percent) that total

less than 0.25 inch for the mountains and 0.50 for the lower country

are disregarded in summarizing days since rain.

The first day on which the measured fuel moisture drops below 20

percent at any observation following a "measurable" rain is recorded

as 1 day since rain. This may be the same day on which the rain

ended. ' Each succeeding day is recorded as an additional day since

rain until a total precipitation of at least 0.25 or 0.50 inch is again

measured.

As long as snow covers the ground at time of observation, days since

rain are zero and remain so until the snow becomes patchy at the

station site. Wlien snow begins to leave the ground bare, again start

recording days consecutively.

At part-time stations when records are resumed, the observer should

determine the necessary data on rainfall from the nearest fuU-tnne

station.

Vegetative condition.—Since there is no exact and practical way

to measure condition of vegetation, certain indices combined with the
42 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

best judgment of the field men are relied upon to determine the status

of this factor. Usually one administrative officer on each administrative unit will make this decision. Instructions differ slightly for

hardwood forests and pine forests.

In the hardwood types, in all cases, the condition of lesser vegetation will be classified; that is, grasses, weeds, and shrubs as distinct

from trees. The classification "green" is used from the time when

grasses, weeds, and shrubs become one-half to three-quarters grown,

continuing through the summer until they are cured by fall frosts.

These changes usually coincide Avith the period when hardwood trees

become more than three-quarters leafed out until the first noticeable

and widespread fall coloration. The spring transition period extends

from the time grasses and weeds begin to spring up in profusion

until they are three-quarters grown. This period usually coincides

with the time the tree leaves reach the "size of squirrels' ears" until

trees are three-quarters leafed out. The fall transition^—shorter and

more abrupt than the spring period—begins when the first fall frost

causes curing of the lesser vegetation and lasts until it is at least 90

percent cured. Tree leaves have usually begun to fall quite generally

throughout the forest by the end of the autumn transition. The

classification "cured" is easy to determine and is used for the remainder

of the year. This period extends from that time in the fall when lesser

vegetation is 90 percent cured into the spring when grasses and weeds

begin the period of rapid growth.

There must be exceptions to the general rules for determining condition of vegetation. For example, on areas where huckleberry brush

predominates, curing may begin much earlier than elsewhere. In

sedgegrass fields where little else grows, the period "green" may first

occur about mid-July or early August. In cases where the spring

transition period is well advanced and a late frost occurs to set back

this early growth, it is necessary to return to "cured" until the vegetation overcomes the setback. During summer and fall, occasional

periods of extended drought cause the lesser vegetation to cure prematurely. Such seasons should be classed as "transition" for the

duration of the drought.

However, if care is used, the classification of vegetation in general

can be made with little chance for serious discrepancy. Figure 17

will be of some assistance in this.

The greatest difficulty comes in mountain areas where elevation

differences produce all three conditions simultaneously on a small area.

In such cases the unit should be rated on the basis of vegetative condition in areas where fire occurrence is greatest. This will most likely

be valleys and lower slopes in the East.

The guides suggested for the hardwood types apply also in the pine

types of the Piedmont and Coastal Plain, with minor modifications.

Mid or late summer in these types usually brings a curing of the

lesser vegetation. Accordingly, "fall transition" should begin with

the arrival of this condition. Killing frosts also usually occur at a

later date in these areas, but "transition" should continue until the

lesser vegetation has been killed. "Spring transition" will usually be

of relatively short duration while growth is starting, as outlined under

hardwood types.

F/6'2'Z>?7%.—Visibility distance is not a factor in determining the

danger-rating index. It is mentioned here only because certain agen-
TREES LEAFLESS TREE LEAVES THE SIZE TREES THREE-QUARTERS TREES COMPLETELY

OF "SQUIRRELS'EARS' LEAFED OUT LEAFED OUT

LEAVES FALLING

GENERALLY

GRASSES, WEEDS, SHRUBS, DEAD'

TO TIME RAPID GROWTH BEGINS

.fmAuwJn^J t

«S THKte-QUAIITtRS TO FULL 'l"ST í 1 VY»"*"E3. WEEDS, SHOUÍS

OHOWII «ILLINO li.

FROST ^

V "•- '

JJjJfjJlÁ "' Jf.«lltiYfiffcf Jt..iCTfXi»WlT * Wi' UJ/tl..i U-.!»L.

o

c

90 PERCENT OR MORE DEAD v-^

CURED

( WINTER)

TRANSITION GREEN

(SPRING) (SUMMER)

Figure 17.—Classification of condition of lesser vegetation.

TRANSITION

(FALL)

CURED

(WINTER)

sa

1^

CO
44 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

cies record it as part of the daily data, and it is a very important

element in fire control planning. When poor visibility accompanies

high fire danger, a different fire control organization becomes necessary. Perhaps more lookont men must be put on the job or special

patrols be sent out to cover predetermined routes. Visibility distance

is considered in prearranged organization plans.

Visibility distance recorded should not be the unaided estimates ot

an observer. Visibility distances should always be determined with

the aid of instruments, such as a haze meter, or by using visibility

scales, such as dark ridge visual range tables. Unguided estimates are

not only meaningless but can be very deceptive. Important decisions

are based on this type of information, so reliability must be paramount. For detailed information on visibility measurement, the

reader is referred to Byram and Jemison (4).

WHEN TO TAKE FIRE-DANGER MEASUREMENTS

In the eastern United States, observations during the fire season

customarily are made at 9 a. m., 2 p. m., and 5 p. m., e. s. t. Lookout

stations manned at 10 a. m. may take their first daily danger measurement at that hour. A standard of 2 p. m. for the afternoon observation is recommended, because danger usually reaches its peak between

1 p. m. and 3 p. m. The 5 p. m. reading normally shows the decline

of daily danger, but may also indicate the less usual but sigiiificant

continuation of dry, windy conditions. When fires are burning uncontrolled, additional dangei' measurements may be useful to aid suppression. Of course, in such cases as many extra observations should

be made as are needed. These need not be made part of the permanent record.

RATING TODAY'S FIRE DANGER

When all the factors conti'ibuting to current fire danger have been

measured, the integration of these measurements into a single index

is a simple mechanical procedure accomplished with the danger meter.

Instructions for the operation of each type of meter are printed right

on the meter.

A fire-danger rating is developed individually for each set of observations. Actual wind velocity and fuel moisture content measured at the particular observation, plus the daily rainfall, accumulated

days since rain, condition of vegetation (and season in the case of the

mountain meters) are weighted automatically by the meter, one at a

time, as the slide or disks are manipulated. The resulting figure is

expressed either as a 5-point class or 100-point burning index, and

represents conditions at the time the particular set of observations was

made.

In the mountain hardwood litter fuels, cumulative drying, indicated

by days since rain, has a more pronounced effect than in the Coastal

Plain grass fuels; hence this factor is given more weight on the

mountain meter.

For statistical reporting purposes each day must be given an over-all

rating. The fire-danr/er ratine/ for the day at any individual station

is considered to be the highest rating computed at any single observation during the day at that station. No averages for fuel moisture
FOREST FIRE-DANGER MEASUREMENT 45

or wind are taken, as they lead to ambiguous situations. Eatings

based on a combination of fuel-moisture content at 0 a. m. aiul wind

velocity at 5 p. m., for instance, are unreliable. For example, if

danger rated class 2 at 9 a. m., class 4 at 2 p. m., and class ;] ut 5 p. m.,

the rating for the (hiy would be class 4, the highest rating computed

at the three observations.

When the ground is blanketed with vSnow, fuel moisture and wind

velocity need not be measured. Record the fire-danger I'ating in such

cases as class 1 or burning index 0, depending on the scale used.

RECORDING OBSERVATIONS

Observations should be recorded on the proper form for the region

in which the station operates. Representative forms used in the East

together with self-explanatory instructions are reproduced on pages

59 to 64.

Accumulated records are indispensable in determining and analyzing trends, in evaluating the success or failure of programs, or in systematic fire control planning in general. Their full value can be realized only by making clear, legible records; currently checking all

data ; filing properly to assure permanence.

All records should be thoroughly checked before filing. This offers

an opportunity to advise the ()l)server of any errors made. Moreover,

it assures that the records on file are reliable.

The cost of handling the records properly is only a fraction of the

cost of obtaining them. It is good business to keep them and use them.

ITEMIZED LIST OF EQUIPMENT AND MATERIALS

FOR A FIRE-DANGER STATION

Quantity Item

Shelter box and supporting posts.

Rain gage stand.

Rain gage and rain measuring stick.

Anemometer.

Fuel-moisture scale and leveling weight.

Bell buzzer.

Knife switch, single-pole, single-throw type.

6 feet Dou})le-lead hook-up wire, approximately No. 16.

12 feet No. 9 galvanized wire for stick supports and holding wire.

2 No. 6 dry cell batteries (Vo volt, telephone type).

4 feet Standard ^^j-inch water pipe, threaded one end for anemometer

support. If anemomet-er ordered takes ^s-inch pipe, use reducer

and short nipple.

2 Pipe straps with 4 1-inch screws, for holding anemometer support

pipe.

Can of light oil for anemometer.

Set of fuel moisture sticks and weathering correction card.

Anemometer correction chart.

Instructions for observer.

Fire-danger meter. TT • j o x >>

^ "Forest Fire Danger Measurement in the Eastern United states.

là.../.-..- Fire danger daily record forms (approximately year's supply).

BILL OF MATERIALS FOR WEIGHING SHELTER

Number pieces '"^'^^ o"^ description •

2_ 4" x 4'' X 7' hardwood posts for shelter support.

2_______ _ %" X 7V>" X 23'^2" top and bottom of shelter.

2..l...\... %" X 7]V' X 36K" sides of shelter.

See footnot«- at <>nd of table.
46 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Number pieces Size and description i

1 Ki''x 5H" X 23'' mounting board for scale.

1 y/' X 5^" X 18" adjusting board for scale.

2 Yi" X \%" X 35" side strips for door.

3 y^" X 1^" X 23" top, center, and bottom strips for door.

2 j^" X Yi" X 35" door stops, sides.

2 y2"x%"x 22" door stops, top and bottom.

1 Ys" X 24" X 36" tempered masonite panel for back.

1 Ys" X 17%" X 20" tempered masonite panel for door.

1 Y>y" X 13" X 20" double-strength window glass for door.

1 9H" X 26H" sheet-aluminum cover for roof.

3 4" strap hinges for door.

18 IK" X Yie" bolts for strap hinges.

2 4"x }4" angle-iron braces for door, with %" screws.

1 4" safety hasp for door, self-locking type, with %" screws.

2 )!" X 2" carriage bolts with wing nuts and 4 washers for scale

adjusting board.

16 2" wood screws for fastening sides of shelter to top and bottom

and to mount scale support.

12 YA" wood screws for fastening panel on back.

12 V/o" wood screws for fastening door stops.

1 10" door chain with holding plat-es and screws.

4 cubic feet of concrete 1:2:3 mixture.

1 small can of waterproof glue.

4 6"x Y2'' bolts with 4 washers for supporting posts.

4 Y4" X YIQ' round-head screws for mounting scale.

4 %"x%6" round-head screws for fastening aluminum roof cover.

1 All sizes are actual dimensions; widths and thicknesses conform to dimensions

available commercially wherever possible.

PARTIAL LIST OF SUPPLIERS OF FIRE-WEATHER

EQUIPMENT

The following lists are prepared merely for the information of

those interested in operating fire-danger stations. The inclusion

of a manufacturer's name implies no endorsement, although the specified item meets general standards set for fire-danger measuring equipment. The lists will be revised currently as additional information

is obtained. Current lists will be furnished upon request.

FUEL-MOISTURE SCALES

A. E. Chisholm

2640 liast Burnside Street

Portland, Oreíí.

FUEL-MOISTURE INDICATOR STICKS

Director

Soiitlieastern Forest Experiment Station

Box 252

Asheville, N. C.

RAIN GAGES

U. S. WEATHEK BUREAU PATTEKN

Science Associates W. S. Jenks & Son

401 North Broad Street 723 Seventh Street Northwest

Philadelphia 8, Pa. Washington, D. C.

FOREST SERVICE TYPE

F. A. Anderson Mannfacturin<i Co. Western Fire Equipment Co.

214 Northwest Flanders Street San Francisco, Calif.

Portland, Oreg.
FOREST FIRE-DANGER MEASUREMENT 47

RAIN-MEASURING STICKS

Leiipold & Stevens Instruments Precision Thermometer & Instrument

444;") Northeast Glison Street Co

Portland 13, Oreg. 14;^4 Biandywine Street

Philadelphia, Pa.

(24" length only)

Western Fire Equipment Co.

San P^rancisco, (\alit'(U'nla

**AIRWAYS" TYPE ANEMOMETERS

(l/t30-mile contact)

Dozier Manufacturing Co. Julian P. Friez & Sons

4223 Grove Street Division of P>endix Aviation Corp.

Oakland, Calif. Baltimore, Md.

M. C. Stewart Co. The Instruments Corp.

Ashburnham, Mass. 1031 P^ast Baltimore Street

Baltimore 2, Md.

A. E. Chisholm Western Fire Equipment Co.

2(;4() East Burnside Street San Francisco, Calif.

Portland, Oreg. (Includes knitV switch, buzzer, coil of

wire, oil can, and correction chart.)

ROUTINE FOR CLEANING ANEMOMETERS

Detailed steps for cleaning several types of anemometers are given

below. Any of the general purpose, light or low viscosity, household,

typewriter, or sewing machine oils are satisfactory for use in these

instruments. When contact points do not close circuit properly, rub

lightly with fine sandpaper and wipe with a clean, dry cloth.

STEWART

It is extremely important that the small socket in which the spindle

of the instrument rests is not disturbed or removed from the housing

in the cleaning process. Allow the anemometer to remain on the support, if accessible, while cleaning.

1. Remove small set screw from side of cup assembly. Do not unscrew bolt in end. Remove cup assembly by sliding it off main shaft,

2. Remove inspection plate by loosening the two holding screws.

3. To remove spindle, unscrew bushing shaft from cast-alloy housing

and slide over spindle.

4. Now carefully remove the spindle. It may be necessary to move

it from one side or the other before it will slide out. Neve?' turn cast

housing upside doum, Ahrays keep in a standing position v)hile

cleaning. If it is turned upside down, the small ball bearings will fall

out.

5. Clean the shaft bushing and the spindle with kerosene.

6. Drop some anemometer oil on each end of the spindle, inside the

top of the bushing shaft, and on the worm gear.

<. Slide spindle into place in housing and replace bushing shaft.

8. Replace cup assembly and small set screw ; also replace the inspection plate, being sure the gasket is weatherproof. The anemometer

is then ready for use.
48 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

When in use, check the need for oil monthly. Remove the inspection plate for observation. If oil is needed, place 1 to 2 drops on the

top and 1 to 2 drops on the bottom of the spindle. Some models

provide a screw on top of the rotor which, when removed, exposes an

oil duct serving the top end of the spindle. In the other models,

the cup assembly must be removed and the oil phiced on the spindle

above the top bearing.

FRIEZ

Allow the anemometer to remain on the support, if accessible, while

cleaning.

1. Remove the tap from the top of the cup assembly and remove

cups and skirt.

2. Remove inspection plate from side of anemometer.

3. Loosen set screw just above plate cover.

4. Slide shaft out of anemometer by lifting from the top.

5. Wash shaft in kerosene. Use deep container and plunge up and

down. Allow excess kerosene to drain.

6. Replace the shaft by inserting into the housing from the top.

Tighten set screw above plate cover.

7. Oil with light oil after assembling. Place 2 drops on the gear

part of the shaft, 2 drops on the bearing at the top of the shaft, and

2 drops on bearing at bottom of shaft.

8. Check contact points.

9. Replace inspection plate. Slip on washer at top of shaft with the

beveled side face down. Replace skirt and cups so as to revolve clockwise. Replace top securing the rotor, and the assembly is complete.

When in use, check the need for oil monthly. Loosen set screw above

inspection plate. Raise cup assembly and spindle. If oil is needed,

place 1 to 2 drops on top bearing, 1 to 2 drops on the gear, and 1 to 2

drops on the bottom of the spindle.

CHISHOLM (1936-1938 MODELS)

1. Disconnect wires and remove anemometer from mount.

2. Take out bolt on top and remove cup assembly.

3. Remove from the bottom of the anemometer the small bolt that

goes through the main shaft. Negative contact wire is also attached

to this screw when the anemometer is in use.

4. Remove electric contact unit by sliding carefully down over the

end of the main shaft.

5. Remove small screw from revolving cylinder near the top. By

turning the top aluminum casting to the left with one hand and holding the cylinder with the other, the two pieces are separated. Remove the spindle from the housing.

6. Now wash all parts with kerosene except the electric contact unit.

Wash by plunging the parts up and down in a deep container. After

washing, allow excess kerosene to drain from the parts.

7. Place about 2 drops of light oil around top of the two roller

bearings attached to^ the shaft. Also add about 2 drops around the

cylinder gear on the inside near the top.

8. Assemble anemometer. Place aluminum casting on top of roller

bearings. Put cylinder up over shaft by turning it to the right until
FOREST FIRE-DANGER MEASUREMENT 49

the holes match in the cylinder and casting. Re])1ace small screw.

Looking in the anemometer from tlie bottom, move the cylinder until

the small pin on tlie gear wheel is face up and in line witli the shaft.

Hold at this point. Now re])lace electric contact unit by sliding carefully up over the shaft into the cylinder. When holding the top of

the anemometer away fi'om you, the contact y)oints should be to tlie

left of the main shaft. Re|)lace small bolt through electric unit and

shaft. Attach cup assembly and replace bolt. The anemometer is

now ready to be remounted.

The anemometer should be oiled once each month when it is in use.

To do this, remove the bolt on top of the cup assembly and place no

more than 3 drops of oil in the hole from which the bolt was removed.

CHISHOLM (1939 MODEL)

Allow the anemometer to remain on the support, if accessible, while

cleaning.

1. Unscrew tap on top to remove cu])S.

2. Remove small screw at junction of top cylinder and housing.

3. Lift top cylinder and si)indle; remove spindle from cylinder.

4. Remove inspection plate from top of housing by removing two

holding screws. Be sure to note position when remoring.

5. Clean the spindle and beai'ing assembly in top of cylinder with

kerosene and a small brush. Wii)e off tlie excess kerosene.

6. Check the contact points on the underside of the inspection plate.

7. Replace ins])ection ¡date /// the same position as when i-emoved.

8. Place 1 to 2 di'ops of light oil on both the top and bottom of the

spindle as well as on the bearing assembly.

9. Assemble by replacing s]nndle in cylinder, replacing cylinder

on housing and securing with the set screw, and replacing cups and

securing with the tap.

When in use, check the need foi' oil monthly. Remove the cups and

observe top bearing. If oil is needed, add 1 to 2 di'ops to top bearing

only.

DOZIER (1938 AND OLDER MODELS)

Allow the anemometer to remain on the support, if accessible, while

cleaning.

1. Remove inspection plate and gear assembly.

2. Check action of contact points by rotating the gear. Adjust the

tension of the brass spring as needed.

3. Remove cups by unscrewing the top.

4. Clean the top and bottom of the spindle without removing it

from the housing. Use kerosene and a small brush. Wipe off the excess kerosene.

5. Place 1 to 2 drops of light oil on both the top and bottom of the

spindle.

6. Assemble by replacing the cups, gear assembly, and the inspection

plate.

Wlien in use, check the need for oil monthly. Remove the cups and

observe the top bearing. Add 1 to 2 drops of light oil to the top bearing if needed.
50 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

DOZIER (1939 MODEL)

Allow the anemometer to remain on the support, if accessible, while

cleaning.

1. Remove the cups by unscrewing the tap.

2. With two pipe wrenches, unscrew the top part of the cast housing

and expose the gear assembly. Do not remove the spindle from the

housing.

3. Clean the top and bottom of the spindle with kerosene and a small

brush. Wipe ofí the excess kerosene.

4. Check the contact points.

5. Place 1 to 2 drops of light oil on both the top and bottom of the

spindle.

6. Assemble by joining the two sections of the housmg, replacmg

the cups, and securing with the tap.

When in use, check the need for oil monthly. Remove the cups and

observe the top bearing. Place 1 to 2 drops of light oil on the top

bearing if needed.

U. S. WEATHER BUREAU—3 AND 4 CUP TYPES

Remove from mount and disconnect wires before cleaning.

1. Unscrew brass oil cup.

2. Loosen set screw and remove cups.

3. Unscrew top bushing and lift spindle.

4. Remove glass cover plate by removing two holding screws. Do

not reviove dials.

5. Clean spindle and top bushing with kerosene. Do not clean

housing a^sseinbly.

6. Blow out oil duct in top of spindle so it is clear of all ohstructions

from the top to the small hole in the side of the spindle at the level

of the top bushing.

7. Inspect contact points.

8. Replace spindle, be sure it is seated properly in the bottom bearing. Replace top bushing. Replace cups and secure set screw.

9. Attach wires and check action of points by rotating cups. Adjust

movable point with set screw, if necessary.

10. Replace glass cover.

11. Place 1 to 2 drops of light oil in top oil duct. Withdraw small,

round inspection plug attached to a chain on the housing on the

opposite side from the glass plate. Through this opening, place 1 to

2 drops of light oil both on the bottom of the spindle and on the spindle

gear. Replace inspection plug.

12. Re^Dlace oil cup on top. Be sure wick feeds from oil cup into

oil duct. Replace with a cotton cord of suitable size if needed. Fill

oil cup with light oil.

When in use, check the need for oil monthly. Inspect bottom bearing by removing the inspection plug. Add 1 to 2 drops of light oil

as needed. Inspect the top oil cup. Add light oil as needed to keep

wick saturated.
FOREST FIRE-DANGER MEASUREMENT 51

WIND CORRECTION CHARTS FOR DIFFERENT TYPES

OF ANEMOMETERS

WIND CORRECTION CHART FOR CHISHOLM ANEMOMETER

(1936-38 model with 4-iiich cups)

NOTE.—Use the 4-ininute count ta})le if winds are variable or Rusty. Use the

2-minute count table only when winds are steady. The corrected wind velocity

in miles per hour is ^iven opposite th(; number of contacts counted.

Steady winds

Contacts in 2 minutes

1

2

3

4

5

6

7

8

9

10____

11

12_---

13_---

14____

15----

16_---

17----

18_-__

19-__-

20----

21-___

22____

23----

24

25----

26----

27__--

28--_-

29___-

30-___

31--__

32----

33_---

34_-_.

35_---

36-37

38-39

40-41

42-43

44-45

46-47

48-49

50-51

52-53

54-55

56-57

1. 5

2. 0

2. 5

3. 0

3. 5

4. 0

4. 5

5. 0

5. 5

6. 0

6. 5

7. 0

7. 5

8. 0

8. 5

9. 0

9. 5

10. 0

11. 0

12. 0

12. 5

13. 0

13. 5

14. 0

14. 5

15. 0

15 5

16. 0

16. 5

17. 0

17. 5

18. 0

18. 5

19. 0

19. 5

20. 0

21. 0

22. 0

23. 0

24. 0

25. 0

26. 0

27. 0

28. 0

29. 0

30. 0

Variable or ^usty winds

( 'ontat'ts in 4 minutes Miles

})er hour

1 _ _ _ _ 1. 0

1. 5

2. 0

2-3-

4-5

6-7 2. 5

8-9 3. 0

10-11 3. 5

12-13 4. 0

14-15 4. 5

16-17 5.0

18-19 5. 5

20-21 6. 0

22-23 6.5

24-25 7. 0

26-27 7. 5

28-29 8. 0

30-31 8. 5

32-33 9. 0

34-35 9. 5

36-37 10. 0

38-39 11. 0

40-42__ 12. 0

43-45 - - 13. 0

' 46-47 13. 5

48-49 14. 0

50-51 14. 5

52-53-- 15. 0

54-55 15. 5

56-57 16. 0

58-59 16. 5

60-61 17.0

62-63 17. 5

64-65 18. 0

¡ ()6-67 18. 5

' 68-69 19. 0

70-71 19. 5

72-75 20. 0

76-78 21. 0

Î 79-82 22.0

i 83-86 23. 0

87-90 24. 0

91-94 25. 0

95-98 26. 0

99-102 27. 0

103-106 28. 0

107-110 29. 0

1 111-114 30. 0
52 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

WIND CORRECTION CHART FOR CHISHOLM ANEMOMETER

(1939 model with 2i^-inch cups)

NOTE.—Use the 4-minute count table if winds are variable or gusty. Use

the 2-minute count tSL\)\e only when winds are steady. The corrected wind

velocity in miles per hour is given opposite the number of contacts counted.

Steady winds3 Variable or gusty winds

Contacts in 2 minutes Miles

per hour Contacts in 4 minutes Miles

per hour

1 1. 5

2.0

2. 5

3.0

3. 5

4.0

4. 5

5.0

5. 5

6. 0

6.5

7. 0

7.5

8.0

8.5

9.0

9. 5

10.0

10. 5

11.0

11.0

11. 5

12. 0

12.5

13.0

13. 5

14. 0

14. 5

15. 0

15. 5

16. 0

16. 5

17.0

17. 5

18.0

18. 5

19. 0

19. 5

20.0

21. 0

22. 0

23.0

24. 0

25. 0

26. 0

27. 0

28.0

29. 0

30.0

1 .. _ ._ 1.0

1.5

2.0

2.5

3.0

3.5

4. 0

4.5

5. 0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9. 0

9.5

10. 0

10.5

11. 0

11.5

12.0

12. 5

13.0

13. 5

14.0

14.5

15.0

15. 5

16.0

16. 5

17.0

17.5

18.0

18. 5

19. 0

19. 5

20.0

21. 0

22.0

23.0

24. 0

25.0

26. 0

27.0

28.0

29. 0

30.0

1 2 2-3

i 3 4-5

i 4 6-7

5 8-9

6

' 7 _.

8

10-11

12-13

14-15

9

10

16-17

18-19

11 20-21

22-23

24-25

26-27

28-29

30-31

32-33

34-35

36-37

38-40

41-44

45-47

48-49

50-51

12

13

14

15

16

17

18

19-20

21

22

23

24

25

¡ 26 52-53

' 27 54-55

28 56-57

, 29 58-59

30

31

60-61

62-63

32

33

64-65

66-67

34 68-69

35 70-71

36

37

38

39-40

41-43

44-45

72-73

74-75

76-77

78-81

82-85

86-90

46-47 91-94

48-49 95-98

50-51

52-53

54-55

56-57

58-59

60-61

62-63 '

99-102

103-106

107-110___

111-114

115-118.

119-122

123-126

1
FOREST FIRE-DANGER MEASUREMENT 53

WIND CORRECTION CHART FOR DOZIER ANEMOMETER

NOTE.—Use the 4-minute count table if winds are variable or gusty. Use

the 2-minute count table only when winds are steady. The corrected wind

velocity in miles per hour is given opposite the number of contacts counted.

SteadV winds

Contacts in 2 minutes

1

2

3

4

5

6

7-8___-

9

i5

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40-41.

42-43_

44-45_

46-47_

48-49_

50-51_

52-53_

54-55.

56-57.

58-59.

60-61.

Miles

per hour

9.

9.

10.

10.

11.

11.

12.

12.

13.

13.

14.

14.

15.

15.

16.

16.

17.

17.

18.

18.

19.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

Variable or gusty winds

Contacts in 4 minutes

1

2-3

4-5

6-7

8-9

10-12___

13-16___

17-19___

20-21___

22-23___

24-25-__

26-27___

28-29 __

30-31-__

32-33.-_

34-35_-_

36-37-__

38-39--_

40-41___

42-43---

44-45-_-

46-47---

48-49.--

50-51---

52-53...

54-55---

5r>-57.--

58-59 - -

60-61 .-

62-63 _-

64-65--.

66-67 --

68-69---

70-71---

72-73 --

74-75---

76-77---

78-79-__

80-82-_.

83-86-_.

87-90---

91-94---

95-98- -

99-102-_

103-106-

107-110-

111-114-

115-118-

119-122.

Miles

per hour

9.

9.

10.

10.

11.

11.

12.

12.

13.

13.

14.

14.

15.

15.

16.

16.

17.

17.

18.

18.

19.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.
54 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

WIND CORRECTION CHART FOR FRIEZ ANEMOMETER

(Weather Bureau dial type with 3 cups)

NOTE.—Use the 4-minute count table if winds are variable or gusty. Use the

2-minute count table only when winds are steady. The corrected wind velocity

in miles per hour is given opposite the number of contacts counted.

Steady winds

Contacts in 2 minutes Miles

per hour

Variable or gusty winds

Contacts in 4 minutes Miles

per hour

1

2

3

4

5

6

7

8

9

10___.

11___.

12___.

13___.

14___.

15___.

16___.

17___.

18-__.

19___.

20___.

21___.

22___.

23___.

24___.

25___.

26___.

27___.

28.__.

29___.

30__-.

31___.

32-33

34___.

35___.

36___.

37___.

38___.

39___.

40-41

42-43

44-45

46-47

48-50

51-53

54-55

56-57

58-59

60-61

62-63

1. 5

2.0

2.5

3.0

3.5

4.0

4. 5

5.0

5. 5

6.0

6.5

7.0

7.5

8.0

8. 5

9.0

9. 5

10. 0

10. 5

11.0

11. 5

12. 0

12. 5

13. 0

13.5

14.0

14. 5

15. 0

15.5

15. 5

16. 0

16. 5

17.0

17.5

18.0

18.5

19.0

19. 5

20. 0

21. 0

22. 0

23. 0

24.0

25. 0

26. 0

27.0

28.0

29. 0

30.0

1

2-3

4-5

6-7

8-9

10-11__

12-13__

14-15__

16-17__

18-19_-

20-21__

22-23__

24-25__

26-27_-

28-29__

30-31__

32-33._

34-35__

36-37__

38-39__

40-41__

42-43__

44-45__

46-47__

48-49 _..

50-51__

52-53-_

54-55__

56-58__

59-62__

63-65__

66-67__

68-69__

70-71__

72-73__

74-75__

76-77--

78-79__

80-82__

83-86__

87-90__

91-94__

95-101_

102-106

107-110

111-114

115-118

119-122

123-126

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12. 0

12.5

13.0

13.5

14.0

14. 5

15. 0

15. 5

16.0

16.5

17.0

17.5

18.0

18.5

19. 0

19.5

20.0

21.0

22.0

23.0

24.0

25. 0

26.0

27.0

28.0

29.0

30.0
FOREST FIRE-DANGER MEASUREMENT 55

WIND CORRECTION CHART FOR FRIEZ ANEMOMETER

(Weather Bureau dial type witli 4 beaded eups)

NOTE.—Use the 4-mimite count table if winds are variable or Rusty. Use the

2-minute count table only when winds are steady. The corrected wind velocity

in miles per hour is given opposite the number of contacts counted.

SteadV winds

Contacts in 2 minutes Miles

])er hour

Variable or gusty winds

Contacts in 4 minutes Miles

per hour

1_

2_

3]

4_

5_

6_

7_

8_

9_

10_

1.5

2.0

2.5

3.0

3.5

4. 0

4. 5

5. 0

5.0

11-12 _ _ 6. 0

13 - - - 6. 5

14 _ 7. 0

15 7. 5

16 8. 0

17 8. 5

18 9. 0

19 - -- --- 9. 5

20 10. 0

21 __ 10. 5

22 11. 0

23 11. 5

24 12. 0

25-26 _ 12. 5

27-28 13.0

29 _- 13. 5

30 14. 0

31 14. 5

32 15. 0

33 15. 5

34 16. 0

35 16. 5

36 _- 17. 0

37 17. 5

38 -- 18. 0

39-40 18. 5

41-42 19. 0

43 19. 5

44-45 - - 20. 0

46-47 21. 0

48-49 - 22. 0

50-51 - - 23. 0

52-54

55-56 - -

24. 0

25. 0

57-59 26. 0

60-61 - - 27. 0

62-63 28. 0

64-65 29. 0

66-67 30. 0

1

2-3

4-5

6-7

8-9

10-11__.

12-13__.

14-15__.

16-17__.

18-20__.

21-23__.

24-26_.

27-29__.

30-31__.

32-33__.

34-35„

36-37_

38-39_ .

40-41__

42-43__

44-45__

46-47__

48-49__

50-52__

53-56__

57-59__

60-61__

62-63__

64-65__

66-67.-

68-69__

70-71__

72-73__

74-75__

76-78_-

79-81__

82-83__

84-86-_

87-90__

91-94._

9.5-98--

99-102-

103-106

107-112

113-118

119-122

123-126

127-130

131-134

1.0

6.0

6. 5

7.0

7. 5

8. 0

8. 5

9. 0

9. 5

10. 0

10. 5

11. 0

11. 5

12. 0

12. 5

13. 0

13. 5

14. 0

14. 5

15. 0

15. 5

16. 0

16. 5

17. 0

17. 5

18.0

18. 5

19. 0

19. 5

20. 0

21. 0

22. 0

23. 0

24. 0

25. 0

26.0

27. 0

28. 0

29. 0

30.0
56 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

WIND CORRECTION CHART FOR FRIEZ ANEMOMETER

(Weather Bureau dial type with 4 cups^—not beaded)

NOTE.—Use the 4-minute count table if winds are variable or gusty. Use

the 2-minute count table only when winds are steady. The corrected wind

velocity in miles per hour is given opposite the number of contacts counted.

Steady winds Variable or gusty winds

Contacts in 2 minutes Miles

per hour Contacts in 4 minutes Miles

per hour

1_ 1. 5

2.0

2.5

3.0

3. 5

4. 0

4. 5

5. 0

5.5

6.0

6. 5

7. 0

7. 5

8. 0

8.0

8.5

9.0

9.5

10. 0

10. 5

11.0

11. 5

12. 0

12. 5

13. 0

13. 5

14.0

14. 5

15. 0

15. 5

16. 0

16. 5

17. 0

17. 5

18. 0

18. 5

19. 0

19. 5

20. 0

21. 0

22. 0

23. 0

24. 0

25. 0

26. 0

27. 0

28. 0

29. 0

30. 0

1 ___ 1. 0

1.5

2.0

2.5

3.0

3.5

4. 0

4.5

5.0

5.5

6.0

6. 5

7.0

7.5

8.0

8. 5

9.0

9.5

10. 0

10.5

11. 0

11.5

12. 0

12. 5

13.0

13. 5

14. 0

14.5

15.0

15. 5

16. 0

16. 5

17.0

17. 5

18.0

18. 5

19. 0

19. 5

20.0

21. 0

22. 0

23.0

24. 0

25. 0

26.0

27. 0

28.0

29. 0

30.0

2 2-3 _

i 3 4-5

4_ 6-7 - _ _

5 8-9

6 10-11- - -

7 12-13

8 14-15- _ - - -

9 _..__

10

11 ___ _ __

16-17

18-19

20-21- -

12

13

22-23

24-25 -

14 _ _ __

15

26-27

28-30

16-17 31-33-

18 34-36

19 37-39

20 40-41

21

22

23-24

42-43

44-45- _

46-48-

25-26 49-52

27 53-55

28 56-57

29 58-59

30-31 60-61-

32

33-34

35

62-61

65-68

69-70

36 71-72

37 73-74

38 75-76

39-40 _ _

41-42

77-80

81-84

43 . 85-87

44 _ _ 88-89

45 90-91

46-48 92-96-

49-51 97-102

52-54 103-106

55-56 _

57-59

107-112_ - -

113-118

60-62 __

63-64

65-67

119-122

123-126

127-134

68-69 135-138

70-71 139-142

72-73 _ _ 143-146
FOREST FIRE-DANGER MEASUREMENT 57

WIND CORRECTION CHART FOR FRIEZ ANEMOMETER

(Ai^wa5^s type-—without dial)

NOTE.—Use the 4-niinute count table if winds are variable or ciusty. Use the

2-minute count table only when winds are steady. The corrected wind velocity

in miles per hour is given opposite the nuniljer of contacts counted.

Steady winds Variable or i^usty winds

Contacts in 2 minutes

Miles

per hour Contacts in 4 minutes

Miles

per hour

0

1 __________

0.0

1. 5

2. 0

2. 5

3.0

3.5

4.0

4. 5

5.0

5. 5

6. 0

6. 5

7. 0

7.5

8.0 -

8. 5

9.0

9. 5

10. 0

10. 5

11. 0

11.5

12. 0

12. 5

13. 0

13. 5

14. 0

14. 5

15. 0

15. 5

16. 0

16. 5

17.0

17. 5

18. 0

18. 5

19. 0

19. 5

20.0

21. 0

22. 0

23. 0

24. 0

25. 0

26. 0

27. 0

28. 0

i 29.0

30. 0

1 1.0

1.5

2.0

2.5

3. 0

3 5

4. 0

4. 5

5.0

5. 5

6. 0

6.5

7. 0

7.5

8.0

8. 5

9. 0

9.5

10. 0

10. 5

11. 0

11. 5

12. 0

12. 5

13.0

13. 5

14. 0

14. 5

15. 0

15. 5

16. 0

16. 5

17. 0

17. 5

18. 0

18. 5

19.0

19. 5

20. 0

21. 0

22.0

23. 0

24. 0

25. 0

26. 0

27. 0

28. 0

29. 0

30.0

2-3

2 4-5 - -_

3 _____ 6-7

4 8-9

10-11

12-13

14-15

5 _ _ _

6

7 _____

8

9

16-17

lS-19

20-21

22-23

24-25

26-27

10

11 ___ _ _

12

13

14 28-29

15 30-31

32-33

34-35

36-37

38-39

40-41

42-43

44-45

46-47

48-49

50-51

52 53

54-55

5()-57

58-59

16 - -

17 - -

18 __ -

19 _ _ _ _

20

21 _ _

22

23 _ - _ _

24

25

26

27

28 - -

29

30 60-61

31 62-63

32 64-65

33 66-67

34 68-69

35 70-71

•^6 72-73

37 74-75

38 39 76-78

40 41 79-82

42 43 83-86

44 45 87-90

4fv-47 91-94

48 49 95-98

^C\ "=»1 99-102

^9 ^'^ 103-106

^4. '^^ 107-110

^6 ^7 111-114

58^59 115-118
58 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

WIND CORRECTION CHART FOR STEWART ANEMOMETER

NOTE.—Use the 4-minute count table if winds are variable or gusty. Use the

2-minute count table only when winds are steady. The corrected wind velocity

in miles per hour is given opposite the number of contacts counted.

Steady winds

Contacts in 2 minutes

1

2

3

4

5

6

7

8

9

10___.

!!___.

12___.

13__-.

14___.

15___.

16___.

17___.

18.__.

19___.

20__..

21___.

22___.

23___.

24___.

25___-

26___.

27___.

28___.

29-30

31___.

32___.

33___.

34___.

35__-.

36___.

37___.

38___.

39___.

40-41

42-43.

44-45.

46-47.

48-49.

50-51.

52-53.

54-55.

56-57.

58-59.

60-61.

Miles

per hour

1. 5

2.0

2. 5

3.0

3. 5

4. 0

4. 5

6.0

6. 5

7.0

7. 5

8. 0

8. 5

9. 0

9. 5

10. 0

10. 0

10. 5

11. 0

11. 5

12. 0

12. 5

13. 0

13. 5

14. 0

14. 5

15. 0

15. 5

16. 0

16. 5

17. 0

17. 5

18. 0

18. 5

19. 0

19. 5

20. 0

21. 0

22. 0

23.0

24. 0

25. 0

26. 0

27. 0

28. 0

29. 0

30. 0

Variable or gusty winds

Contacts in 4 minutes

1

2-3

4-5

6-7

8-9

10-11._

12-13__

]4-15-_

16-17__

18-19__

20-21__

22-23__

24-25-_

26-27__

28-29._

30-31__

32-33__

34-35._

36-39__

40-41__

42-43__

44-45__

46-47__

48-49__

50-51__

52-53__

54-55..

56-57__

58-60._

61-62_.

63-64._

66-67._

68-69..

70-71..

72-73..

74-75._

76-77._

78-79..

80-82..

83-86..

87-90..

91-94..

95-98..

99-102.

103-106

107-110

111-114

115-118

119-122

Miles

per hour

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9. 0

9.5

10.0

10. 5

11.0

11.5

12.0

12.5

13.0

13. 5

14.0

14. 5

15.0

15. 5

16.0

16.5

17.0

17.5

18. 0

18.5

19. 0

19.5

20.0

21. 0

22.0

23.0

24.0

25.0

26.0

27.0

28. 0

29.0

30.0
FOREST FIRE-DANGER MEASUREMENT 59

PREPARATION AND DISTRIBUTION OF FIRE-DANGER

DAILY RECORD AND FIRE-DANGER DAILY SUMMARY

INSTRUCTIONS FOR PREPARING FIRE-DANGER DAILY RECORD

(FORM 14-R-7 REV. DEC. 1947)

(Form l-l-R-7 was adaptiMl iji-iniarily for use by State agencios.)

Note to ohscrvcrs.—The instructions given belo^Y, and the form

shown in fio:ure 18, are meant to be used with the 100-point scale firedanger meter (meter H-W) issued by the Southeastern Forest Ex])eriment Station. There has been no change in the instructions to firedanger station observers regai'ding the operation of the danger station

or in the procedures used in taking and recording fire-danger data.

The same data are used in c()m])uting burning index from 1 to 100 as

were used to compute danger chiss from 1 to 5. The burning index

may be converted to danger class if desired—see dotted lines on outer

circle of meter 5-W, or refer to the table printed on the back of meter

5-W at the bottom.

Golmnn 2, state of vegetation.—Record "G" (for green), ''T" (transition), or "C" (cured). See p. 42 for definitions of G, T, and C.

Colwnns 3^ 6^ 9; fuel mohture percent,—Record to nearest onetenth percent up to 20 percent; to nearest one-half percent above 20

percent. Record "S" (for snow) if ground is covered with snow, and

do not read sticks.

Columns 4, '/', 10; wind velocity miles per hour.—Record to nearest

half-mile according to wind correction chart. If cups are not turning,

record as zero.

Columns 6^ 8, 11 ; burning index.—Record burning index given by

Southeastern Forest Experiment Station fire-danger meter (type

5-W). See instructions on back of meter for procedure in operating

meter. Record 0 (zero) when snow blankets the ground.

Columns 12., IS; precipitation began and ended.—Record time to the

nearest 15 minutes and add ^'A" or ''P" to denote a. m. or p. m. Record

DN if rain started and stopped during night. Record ''Cont.'' (for

continued) in column 13 if it is still raining at 5 p. m., and show time

of ending next day. For i)urposes of recording rain, the day begins

and ends at 5 p. m. instead of midnight. Write the word ''Showers"

in Columns 12 and !?> if there is more than one start and stop in the

24-hour period 5 p. m. to 5 p. m.

Column IJ4, amount of precipitation.—Record in inches and hundredths like dollars and cents (5 hundredths = 0.05; 1 inch and 25

hundredths=1.25, etc.). If less than 0.01 (one hundredth), record

"T" (for trace).

Coliumn 15., total precipitation.—Record amount of rain from Column 14, adding together rains that are not separated by drying weather

(fuel moisture less than 20 percent). Disregard rains that total less

than 0.25 inch; that is, do not record these small rains in Column 15.

Do not repeat figure each day, record only when a change occurs.

At beginning of aHew month, record the last entry in Column 15 from

preceding month. Disregard small rains that, following close to large

rains, will cause the meter reading to increase.
60 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Col/iimn 16^ days sÍ7we rain.—Record days since "Total Precipitation" computed in Column 15. Record "0" (zero) if the fuel moisture

stays 20 percent or higher. Record "1" if the fuel moisture drops below

20 percent. This may be the same day as the rain. After "1" dav is

recorded, record days consecutively between rains entered in Column 15.

Column 17^ turning index for the day,—Record the highest burning

index computed in Columns 5, 8, or 11. Do not average.

Form 14-R-7

Rev. Dec. 1947

State

FIRE BAIÎGER DAILY RECORD

(Instructions on back of sheet)

District Station

Received,

Checked

Recorded

Month 19 Observer

5

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Í

tu;

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«H

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to

9 A.M. D5T 2 P.M. BST 5 P.M. íST

PRECIPITATION

DAILY

STJî,it-îARY

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Ti O

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(-

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for the past

24 hours

(5 PM to 5 ni)

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1

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3

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ô

7

8

9

10

^?.

1.-^

14

15

15

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Figure 18.—Fire-danger daily record (Form 14-R-7).
FOREST FIRE-DANGER MEASUREMENT 61

FIRE-DANGER DAILY RECORD (FORM 14NF-R-7, REV. SEPT. 1947)

(This form is designed for use on the national forests of Region 7.)

The data obtained at eacli station will be recorded on Form 14

(ñg. 19) by the observei* imniediately after each measni'enient. The

observer will make one carbon co})y to be retained atthe danger station.

The original copy should be foi'wai'ded to the district office at the end

of each month. During Hre season two copies of Form 11 will be

form l4Rr-R-7

Rev. Sept. 1947 FIRE DANGER DAILY RECORD

Recelved_

Checked

Recorded_ by

8

CO

CD en

to CO

M fô CO*-• 8

*-> 00 N3 cn -. (O ^ O u> 00 sj CD cn >;^ w to H' (-• Day of the Month

^^ Visibility

ID

8

3

' 'J State-T/eather

Í»- Wind Direction

ai Fuel Moisture

a> Wind Velocity

<¡ Purning Index

CO Visibility

CO

8

CÛ State-^'e^ther

O Find Direction

M FUPI î'oisture

CO "ind Velocity

H" Burning Index

Visibility

o

o

CJl State-Weather

cr> rind Direction

-^ Fuel ?îoir.ture

-

CD rind Velocity

1

1 UD Burning Index

CO

O

" c .-r ? ^5

|-< o o 0) HH

Ü1 L: . Kl

:. "^ S 'S ^

<T>

pu

^ o

I

CO Avg. Visibility

g

C/î

gMi

^ CO Vegetation State

to Total Précipitation

CO

Oí

"'lEiber of Days

?ince Pain

_ J

CO

-4 Burning Index

for Day

Figure 19.—Fire-danger daily record (Form 14NF-R-7).
62 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

maintained in the district office from telephone reports made by the

danger-station observer. At the end of each month the district copies

should be checked against the observer's original for mistakes in posting or misunderstanding over the telephone. The observer's original

copy and one corrected copy of Form 14 should be forwarded to the

supervisor, the other retained in the district files. If district copies

of Form 14 are not maintained currently by telephone, as will normally

be the case out of fire season, the district and supervisor's copies

may be prepared at the end of the month from the observer's original

form. If the daily summary section of Form 14 and burning index

are not filled in by the observer, this should be done in the district

office before mailing the copies to the supervisor's office.

INSTRUCTIONS FOR PREPARING FIRE-DANGER DAILY RECORD

(FORM 14NF-R-7, REV. SEPT. 1947)

Columns marked by an asterisk (*) must be filled in by all stations.

Cohnnns S, c9, H, and 23; visibility.—Record estimated distance at

which i/g-acre fire can be seen to nearest mile. Column 23 is average

of columns 2, 8, and 14.

Columns 3^ ,9, and 15; state of loeather.—Use symbol as follows:

1—Clear : clouds cover less than 4 tenths of sky.

2—Partly cloudy : clouds cover 4 tenths to 7 tenths of sky.

3—Cloudy : clouds cover S tenths or more of sky.

4—Dense or thick fog : visibility less than one-half mile due to fog.

5—Haze (other than smoke) : visibility less than 6 miles due to haze.

6—Light rain : not sufficient rain to form puddles or to wet through ordinary

clothing within 5 minutes.

7—Moderate or heavy rain : puddles form rapidly ; ordinary clothing wets

through in 1 to 3 minutes.

8—Light snow : visibility more than t)ne-half mile.

9—Moderate or heavy snow : visibility less than one-half mile.

10—Thick or dense smoke : visibility less than one-half mile.

Columns 4^ 10. and 16; wind dirrrtion.—Use symbol as follows:

1—NE 3—SE 5—SW 7—NW 9—Variable or unknown

2—E 4—S 6—W 8—N 0—Calm

""Colunim 5, 77, a}\d 17; fuel nioisture.—Recova to nearest one-tenth

percent up to 20 percent ; to nearest one-half i)ercent above 20 percent.

Eecord "S" (for snow) if ground is covered with snow and do not

read sticks.

"^'Columns 6,12, and 18; wind velocity.—'R^QOVA. to nearest half-mile

according to wind correction chart. If cups are not turning, record

as zero.

Columns 7,13, and 19; hnrning index.—Record burning index given

by Southeastern Foi-est Experiment Station fire-danger meter. Record zero when snow blankets the ground.

^Columns 20 and 21, precipitation legan and 6n¿6¿.—Record to

nearest 15 minutes and add "A" or'T'' to denote a. m. or p. m. Record

DN if rain started or stopped during night. Record "Cont." ( for continued) in column 21 if it is still raining at 5 p. m. and show time of

ending, next day. For purposes of recording rain the day begins

and ends at 5 p. m. instead of midnight. Write the word "Showers"

in columns 20 and 21 if there is more than one start and stop in the

24-hour period 5 p. m. to 5 p. m.
FOREST FIRE-DANGER MEASUREMENT 63

"^Column 22^ amount of fTeGÍ¡ntation,—Record in inches and

hundredths like dollars and cents (5 huiidredtlis = ().()r) ; 1 inch and 25

hundredths = 1.25, etc.). If less than 0.01 (one hundredth), record

"T^' (for trace).

'^Column ^4? vegetation stage.—Eecord 1 (cured), 2 (transition),

and Í] (i>reen). (See p. 42 foi* deiinitions.)

"^Column Í26., total precifitation.—Record amount of rain from

column 22, addin^Li tooether rains tliat are not separated by dryin<^

weather (fuel moisture less than 20 percent). Do not repeat fi<i;iire

each day; record only Avhen a change occurs. Disregard rains that

total less than 0.25 inch. At beginning of a new month record total

carried over from preceding month. Disregard small rains that, following close to large rains, will cause the meter reading to increase.

Column 26, days since ram.—Record days since Total Precipitation

computed in column 25. Record ''0'' (zero) if the fuel moisture stays

20 percent or higher. Record "1" if the fuel moisture drops below

20 percent. After "1" day is recorded, record days consecutively

between rains entered in column 25.

Cohiinn ;?7, hvrvivg ¡nde.i' for the day.—Record highest burning

index computed in columns 7, 13, or 19.

FIRE-DANGER DAILY SUMMARY FOR THE DISTRICT

(FORM 15-R-7, REV. SEPT. 1947)

Form 15 (fig. 20) should be prepared each month. Out of fire

season, or when only one station is operating on a district, it will only

be necessary to complete the heading and lire occurrence section. This

may be done at the end of the month on back of observeras Form 14

when it is received. During fire season, or whenevei* more than one

station is in operation on a district, this form should be posted daily

from data recorded on Form 14. The data from column 23 on Form 14

should be posted under the name of the danger station, and the

district average computed to the nearest mile. The data from column

27 should be posted under the name of the danger station. The district average burning index should be recorded to the nearest unit from

1 through 17 and to the nearest unit of 5 from 20 through 100. Odd

figures followed by .5 should be thrown up, even figures thrown dowai.

For example: 17 and 18, average 17.5, should be recorded as 18; 35

and 40, average 37.5, should be thrown up to 38 and recorded as 40.

Fire organization class on duty today and predicted class needed for

tomorrow should be recorded as per the fire plan, which is according

to danger class at present. Tlie danger-class equivalents according to

burning index are tabulated on the burning index meter. ^ A^Hien only

one station is in operation on a district, the data on visibility and

burning index need not be entered on Form 15. The fire occurrence

section, however, should be completed each month. If no fires, write

NONE. Two copies of Form 15, together with the observer's original

Form 14 and one corrected Form 14, should be mailed to the supervisor's office at the end of each month. The supervisor's office should

forward the observer's original Form 14, and one copy of Form 15,

to the Southeastern Station each month as soon as all the records are

received from the districts.
64 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Form 15-R-7

Rev» Sept. 1947 FIRE DAlTGîR DAILY SlTL^'ARY FOR THE DISTRICT

03 g S

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District

Averaf^e

i

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District

Averace

^

Fire Organization

Class on Duty

Today

Predicted. Class

TTeeded for

Tomorrow

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These data recorded by_ _Checked by_

Figure 20.—Fire danger daily summary (Form 15-R-7).

POINTS TO FOLLOW IN OPENING AN INTERMITTENT

FIRE-DANGER STATION

Scale shelter.—Check firmness and alignment of shelter post and

mounting of shelter on post. Tighten and align post and box if

needed.

Check box for leaks, and door for proper closure. Make necessary

repairs.

Annually check condition of paint. Eepaint outside as needed.

Do not repaint inside.
FOREST FIRE-DANGER MEASUREMENT 65

Scale.—Annuiilly check scale, iiu'liidino' pivot pin, for corrosion and

rust. Clean scale, usino- only a clean, dry rag and pointed stick to

clean the pivot pin and seat, and rei)lace rusted hook if needed.

Fuel-moistvir sticks.—Remove any lar^^e twii>-s or limbs that have

fallen near or over the i-ack.

Measure the height of the wire rack so the moisture sticks will be 8

inches above the litter.

Be sure bare ground or dirt is not showing under the rack or around

the edges. If the soil is showing, place enough leaves or litter under

the rack to cover up the bare area.

Be sure the sticks liave been exposed continuously to the weather.

Replace w^ith new sticks if the exposure has been interrupted for any

reason.

Anemometer.—Check for alignment. Plumb if necessaiy.

Thoroughly clean the anemometer, following the proper routine for

the type instrument in use.

Rain gage.—Check support for firmness and alig]iment. Repair

and level as needed.

Check can, tube, and funnel for leaks; check funnel for shape.

Restore round shape and repair leaks as needed.

Check measuring stick for legibility. Replace if in poor condition.

POINTS TO FOLLOW IN CLOSING AN INTERMITTENT

FIRE-DANGER STATION

Scale shelter.—^AVeatherproof and lock door.

Anemometer.—Discomiect contact wires, remove instrument from

support and store in safe place.

Wipe threads on support with an oily rag.

Rain gage.—For short periods of vacancy, remove funnel and tube

and store in safe place. Can should remain exposed, to collect precipitation during vacancy.

For prolonged pei'iods of vacancy, remove entire gage from support

and store in a safe place.

FveJ-moisture sticks.—AWo^y sticks to be exposed \\\ the normal

manner for the full period specified on the weathering correction card.

Do not interrupt this period even when leaving the station unoccupied.
66 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

INSPECTOR'S REPORT—FIRE-DANGER STATION

INSPECTION

state or Forest District Station

Date C>bserver Inspector

Inspection Rating

INSTUUCTIOISS : Numbers in parentheses refer to pages where appropriate instructions may he found in the handbook "Forest Fii'e-Danger iMeasurement in

the Eastern United States."

Opposite each coniUtion listed l)elow, enter "1" if condition is correct, or "0"

if incorrect. List all incorrect items by number at bottom of page, enter appropriate remarks covering repairs or adjustments or training given during the

inspection, and indicate where follow-up is needed.

When inspection is completed, compute Inspection Rating and enter al)ove in

space provided. This inspection covers 100 items, and the rating is determined

by adding all the conditions checked "1" or by subtracting the number of "0"

conditions from TOO. A minimum rating of 00 is considered standard. Substandard ratings indicate the need for additional training and closer supervision by

the district headquarters. All ratings should be discussed freely with observers.

Rain nica

1. Gage exposure satisfactory

(28)

2. Protected from violent winds. __.

3. Gage support adequate (128) __.

4. Support firm in ground (28)

5. Funnel top level (28)

6. Funnel top correct height

(28)

7. Funnel top undamaged (38)

8. Gage leakproof

9. Gage clean inside (38)

10. Inner tube undamaged

11. Tube removed during freeze__ .

12. Measuring stick intact (28)

su renient

13. Stick legible, handled carefully

14. Rain measured correctly (40)_

1;"). Measured to nearest 0.01"

16. Time recorded nearest 15

minutes .

17. Time recorded correct columns

18. Gage emptied after each reading

10. Amount of rain recorded cori-ectly

20. Less than 0.01" recorded as

*'T" .

Remarks—Rain measurement
FOREST FIRE-DANGKR MEASUREMENT 67

Sheet 2—Station liisiiectioii Station

)V'///Y/ tncdsHrcnient

(Anemometers slionld not be repaired oi- adjnsted except l)y trained iK'i'Soniiel )

21. Anem. exposure satistfactory

(29)

22. Cups cori-ect lUMiild (21))_^___ .,

23. Anem. moiintinji satisfactory

(2S)

24. Post firm in ^ronnd (2."))

25. Anemometer i)Uim)) il^S)

26. Anemometer firm on post

27. C'ups not l(K)se or damai;ed

2.S. Cups all face same way

20. Cups rotate clockwise

;U). Cups I'otate freely with no

binding

31. Anemometer clean inside

32. Oiled monthly, correct amt.

of oil

33. Contacts close every 12-15

turns

34. Contacts clean, adjustment

correct

35. Anemometer not worn excessively

36. Casing- leakproof

.">7. Wiring soldered or taped

*»S. Wiring not loose or ln"oken__

3!>. Buzzer or llaslier in order

40. Switch in ordei- .

41. Battery condition satisfactory

42. Circuit has enough batteries.

43. Wind chart posted in shelter-

(25)

44. AVind chart used correctly

(40)—

45. Uses watch to time wind

(3i))

40. Start time end of 1st signals47. Wind recorded nearest I/2

mile

4S. liecorded "0" when cups not

turning

40. Times wind at least 2 nnnutes

50. Extra readings on gusty days

days (40)

RcuKirks—Wind tn vu s n renient
68 HANDBOOK 1, U. S. DEPARTMENT OF AGRICULTURE

Sheet 3—Station Inspection Station

51.

52.

53.

54.

55.

56.

57.

58.

59.

60.

61.

62.

63.

64.

65.

66.

67.

69.

70.

71.

72.

73.

74.

76,

77,

Fuel-moisture

Shelter constrnction adeqnate

(25)

Shelter leakproof (37)

Paint in g:oocl condition (37) __

Shelter hrm on post (37)

Post firm in ground (37)

Shelter does not lean

Door does not bind

r)0(>r ojiens in lee of wind ( 26) _

Door provided with lock

Shelter clean inside (25)

Instruction sheet posted (25)_

Scale mounting adjustable

(25)

Scale firmly mounted

Scale convenient height ( 26 )

Scale figures clean and legibleAdjusting board approx. level

(25)

Scale pivot does not bind ( (>5 ) _

Pointer swings freely full

scale --

Slider firm but not loose

Hook does not bind __--

Hook adequate to hold sticks.

Balancing weight stored in

shelter

(Jhecks scale correctly (38)

Checks balance once a week

(38)

Scale l)alanced (38)

Sticks re4)laced regularly

Stick exposure satisfactory

(22) :

'mea

78.

79.

80.

81.

82.

&S.

84.

85.

86.

87.

88.

89.

90.

91.

92.

93.

94.

95.

96.

97.

98.

09.

100.

sûrement

Vegetation unmolested at site

(20)

Sticks correct height (35)___

Stick support adequate (35) _

Sticks held on support (36)__

Sticks approx. horizontal

(35)

Proper side up (35)

Protected from animals (21 )_

Protected from washing (21 ) _

Sticks not shaded by shelter

(23)

Adequate litter under sticks

(37)

Sticks clean and intact (37)_

Handled by edges (37)

Weatliering card posted

Dates correct on card (39)

Dates complete on card (39)_

Slider set correctly (39)

Waits till sticks stop swinging

Sticks swing free of shelter

(25)

Taps pivot before reading

( 39)

Scale read properly (39)

Readings entered on standard

form

liecoi'ds "S" for snow (59)

State of vegetation recorded

(41)

Remarks—Fuel-moisture measurement

U. S. GOVERNMENT PRINTING OFFICE: 19B0
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