IMPROVEMENTS IN APPARATUS FOR PRACTICAL METEOROLOGY
Year: 1880

page_text: LETTERS PATENT to Friedrich Hermann Felix Engel, Civil Engineer and
Patent Agent, in the City of Hamburg, Germany, for an Invention of
" IMPROVEMENTS IN APPARATUS FOR PRACTICAL METEOROLOGY." A commu-
munication from Wilhelm Klinkerfues, Doctor of Philosophy, Professor and
Director of the Royal Observatory at Göttingen, in the German Empire.
PROVISIONAL SPECIFICATION left by the said Friedrich Hermann Felix
Engel at the Office of the Commissioners of Patents on the 22nd December
1880.
FRIEDRICH HERMANN FELIX ENGEL, Civil Engineer and Patent Agent, in the
City of Hamburg, Germany. "IMPROVEMENTS IN APPARATUS FOR PRACTICAL
METEOROLOGY." A communication from Wilhelm Klinkerfues, Doctor of Philosophy,
Professor and Director of the Royal Observatory at Göttingen, in the German
Empire.
This instrument, which is constructed for indicating dry, changeable, or rainy
weather, allows of taking direct observations based upon the combined influence of
the air-pressure, air-moisture, and direction as well as changes of wind.
The instrument requires either the metallic vacuum box (Vidi's system) or the
ring (Bourdon's system) of an aneroid barometer, and according to the application
of one or other of these parts the construction must be modified. If a vacuum
box after Vidi's system is applied the following is a description of the
instrument:-
Upon an axle, which serves as shaft for the indicating hand of the instrument,
an arm or lever is fastened, and gives an inertia for turning the axle. Within a
short distance of the axle, and parallel or about parallel to it, a string of hygroscopic
threads, for instance, human hair, is fastened and connected to the arm by means of an
eye or other suitable attachment. The arm exerts a certain pressure on the hygroscopic
string, which latter consequently forms a convex curve." The convexity enlarges
and diminishes with the degree of the relative moisture of the air, and accordingly
the hand falls or rises. At same time the degree of convexity of the hygroscopic

page_text: string is subject to the influence of the air pressure, as it is fastened with one end
to the diaphragm of the metallic box of an aneroid barometer. If the air pressure
rises the degree of convexity diminishes, whilst the convexity is larger if the air
pressure falls. The relative influence of the diaphragm of the aneroid box and of
the hygroscopic string upon the motion of the hand can be adjusted by altering
the length of the string or by other simple and known mechanical means of
adjustment.
Instead of attaching the indicating hand direct to the axle of the instrument, the
turning motion of the axle may be transported to the hand by an intermediate
segment and small pinion, and this gives a means to enlarge the motions of the
hand if desirable.
The scales in front of the instrument, along which the hand moves, consist of
two concentric discs, which can be turned by the observator without influencing
the motion of the hand. The smaller or inner disc is at its periphery furnished
with a scale showing the different directions of the wind; this scale is called the
wind-scale. The outer scale, which is called the weather scale, shows at its periphery
all gradations of the weather from dry to much rain.
Instead of marking the gradations by letters or by words only a scale changing
accordingly from white to dark may be used. The indicating hand may be arranged
to move either partly behind, between, or before the scales, as convenient. The
scales can be made of glass or other transparent or nontransparent material, as
desired.
The mode of practical application of this instrument is as follows:-For taking,
for instance, in the afternoon a prognosis of the weather of the following day, in
the fore-noon already the weather scale must be turned thus, so as to bring the
present weather in coincidence with the indicating hand, and at same time the
wind scale must be turned in a position to bring the present wind direction likewise
in coincidence with the hand of the instrument. In the afternoon the band will
have made a movement in either one or other direction, and will, in case no change
of wind has occurred in the meantime, directly show to the observer the weather
that may be expected for the following day.
In case the direction of wind has changed the weather scale must first be turned
so far as to bring the character of the weather of the fore-noon in coincidence with
the new wind direction. The hand will then show to the observer the coming
weather. In a fully analogous way a prognosis taken at the fore-noon is to be
based upon the adjustments of the scales in the afternoon of the preceding day.
Instead of a metallic vacuum box after Vidi's system a ring after Bourdon's
system can be used for the movements of the hand produced by the changes of the
air pressure. The dimensions of the instrument will be smaller, and the con-
struction and adjustment be simplified if Bourdon's ring is used. The Bourdon
ring carries at its ends projections, between which the hygroscopic string is
fastened. This string supports at about its middle a short lever or a metallic arm,
which is in connection with the indicating hand of the instrument, and in an
analogous manner, as before described, the greater or smaller convexity of the
string, depending upon the combined influence of the air-pressure and the relative
moisture of the air, operates the hand in front, between, or behind two scales of a
similar construction as that before described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Friedrich Hermann Felix Engel in the Great Seal Patent Office
on the 22nd June 1881.
FRIEDRICH HERMANN FELIX ENGEL, Civil Engineer and Patent Agent, in the
City of Hamburg, Germany. "IMPROVEMENTS IN APPARATUS FOR PRACTICAL
METEOROLOGY." A communication from Wilhelm Klinkerfues, Doctor of Philosophy,
Professor and Director of the Royal Observatory at Gottingen, in the German
Empire.
This instrument, which is constructed for indicating dry, changeable, or rainy
weather, allows of taking direct observations based upon the combined influence of
the air-presure, air-moisture, and direction as well as changes of wind. The
instrument requires either the metallic vacuum box (Vidi's system) or the ring
(Bourdon's system) of an aneroid barometer, and according to the application of one
or other of these parts the construction must be modified. If a vacuum box, after
Vidi's system is applied, the following is a description of the instrument :-
:―
Upon an axle, which serves as shaft for the indicating hand of the instrument, an
arm or lever is fastened and gives an inertia for turning the axle. Within a short
distance of the axle and parallel, or about parallel to it is a string of bygroscopic
threads, for instance human hair, is fastened and connected to the arm by means of
an eye or other suitable attachment. The arm exerts a certain pressure on the
hygroscopic string, which latter consequently forms a convex curve. The convexity
enlarges and diminishes with the degree of the relative moisture of the air, and
accordingly the hand falls or rises. At same time the degree of convexity of
the hygroscopic string is subject to the influence of the air pressure, as it is fastened
with one end to the diaphragm of the metallic box of a aneroid barometer. If
the air pressure rises the degree of convexity diminishes, whilst the convexity is
larger if the air-pressure falls. The relative influence of the diaphragm of the
aneroid box and of the hygroscopic string upon the motion of the hand can be
adjusted by altering the length of the string, or by other simple and known
mechanical means of adjustment.
Instead of attaching the indicating hand direct to the axle of the instrument the
turning motion of the axle may be transported to the hand by an intermediate
segment and small pinion, and this gives a means to enlarge the motions of the
hand if desirable.
The scales in front of the instrument along which the hand moves consist of two
concentric discs, which can be turned by the observer without influencing the
motion of the hand. The smaller or inner disc is at its periphery furnished with a
scale showing the different directions of the wind; this scale is called the wind-
scale.. The outer scale, which is called the weather-scale, shows at its periphery all
gradations of the weather from dry to much rain.
Instead of marking the gradations by letters or by words only a scale changing
accordingly from white to dark may be used.
The indicating hand may be arranged to move either partly behind, between, or
before the scales, as convenient. The scales can be made of glass or other
transparent or nontransparent material as desired.
The mode of practical application of this instrument is as follows:-For taking,
for instance, in the afternoon a prognosis of the weather of the following day, in
the fore-noon already the weather scale must be turned thus so as to bring the
present weather in coincidence with the indicating hand, and at the same time the
wind scale must be turned in a position to bring the present wind-direction
likewise in coincidence with the hand of the instrument. In the after-noon the

page_text: hand will have made a movement in either one or other direction, and will, in case
no change of wind has occured in the mean time, directly show to the observer
the weather that may be expected for the following day. In case the direction of
wind has changed, the weather scale must first be turned so far as to bring the
character of the weather of the fore-noon in coincidence with the new wind
direction.
The hand will then show to the observer the coming weather in a fully analogous
way; a prognosis taken at the fore-noon is to be based upon the adjustments of
the scales in the after-noon of the preceding day.
Instead of a metallic vacuum box after Vidi's system a ring after Bourdon's
system can be used for the movements of the hand produced by the changes of the
air-pressure. The dimensions of the instrument will be smaller and the construction
and adjustment be simplified if Bourdon's ring is used. The Bourdon ring carries
at its end projections, between which the hygroscopic string is fastened. This
string supports, at about its middle, a short lever or a metallic arm which is in
connection with the indicating hand of the instrument, and in an analogous manner,
as before described, the greater or smaller convexity of the string, depending upon
the combined influence of the air pressure and the relative moisture of the air,
operates the band in front, between, or behind two scales of a similar construction
as that before described.
The accompanying Sheet of Drawings represents different methods of carrying
this Invention into effect. Figs. 1, 2, 3, and 4 represent an instrument constructed
with Vidi's box, and Figs. 5 to 10 show instruments with which Bourdon's ring is
used.
Fig. 1 is a longitudinal section, and Fig. 2 a cross section of the first named
instrument, whilst Fig. 3 is a section after line o, o, and Fig. 4 is an outer front
view of the instrument.
2
A is a metal casing with openings B, B, which allow the atmosphere sufficiently
free entrance to the acting parts, influencing the indicating hand z; a is the shaft,
to one end of which hand is fastened; c is a hygroscopic string, preferably made
of human hair, and b a short arm or lever fastened to shaft a, which arm rests
upon or is attached to string c, which latter is by this arm, and if required in
addition, by another lever or weight t fastened to a, pressed down in a convex curve,
as will be seen in Fig. 1. The string c is with its one end attached to lever D
that is in connection with the diaphragmn of the aneroid box R of the instrument,
in a manner or construction similar or equivalent to that used for common aneroid
barometers. Figs. 1 and 2 show this construction, in which lever D is with one
end supported by the edge of bracket E, and with its other end by the spiral
spring G, whilst H is the connecting mechanism between lever and diaphragm.
The other end of string c is attached to an adjustable spring arm or other adjustable
part of the casing. In the construction shown in Figs. 1 to 4, v is an adjusting
screw with conical point, by means of which the free end of spring to which c is
fastened can be brought nearer to or farther from box R, as may be found necessary
either for slackening or tensioning string c.
K represents a protecting glass plate in front of the instrument.
The action of the instrument. is as follows:-If the air pressure rises the
diaphragm of box R is pressed inward, and consequently string c is strained in
accordance with the movements of the diaphragm and arm b lifted; shaft a is
consequently turned in direction to the right hand, and finger Z rises on weather-
scale P. At same with the movements of the diaphragm the string c is
influenced by the changes of the relative moisture of the air, and if this moisture
diminishes the string is strained, and moves in addition to the influence of the
aneroid box hand z further upward on scale P, whilst it must rise less, or will fall
if the degree of relative moisture increases during a rise of the air pressure. The
shading of scale P illustrates the different stages of the weather from much rain
upward to very dry.
As it is important when forming a prognosis of the coming weather to be

page_text: able to take in account the alterations of the direction of the wind within a certain
time, a second small scale P¹ is placed in front of the instrument, and concentrical
to scale P. This scale P¹, which is called the wind scale, is furnished with divisions
showing the different wind directions from North to South, and is used in the
following manner :-
For taking, for instance, in the afternoon a prognosis of the coming weather of
the next day, the weather scale P is in the forenoon already turned by means of
button m in either one or other direction, as required, to make hand z show on
scale P to the present state of weather, and scale P' is by means of button m¹
afterwards turned to make hand z likewise show to the present direction of the
wind. If no change of wind has occurred in the mean time hand z, which may
during this time have risen or moved down on scale P, will in the afternoon
directly show to the observer the coming weather of the next day. If however a
change of wind has occurred the weather scale P must before taking the observation
have been turned either to the right or to the left, according to the change occurred
so as to bring the position of scale P as it was in the morning in coincidence with
the wind direction of the afternoon. After this has been done hand z will show to
the observer the coming weather.
The other Figures of the Drawings illustrate modifications in which Bourdon's
aneroid ring is brought in connection with the hygroscopic string instead of an
aneroid box, as before described. H' represents in all these Figures the Bourdon ring,
the action of which is commonly known. In Figs. 5 and 6 the ends t of the ring
are furnished with arms, between which string c is suspended in an adjustable
manner.
According to the changes of the air-pressure ends t are adjusted closer to or
removed from each other, in consequence of which string c will form a deeper or
plainer curve. At same time the degree of convexity of this curve will be
influenced by the moisture of the air in a similar way as before described.
According to the rise or fall of the curve of string c an arm k fastened to
segment-lever b6 turning on a pin e¹ will be lifted or lowered, and will by means
of gearing & turn a pinion n fastened to shaft a of hand z in either one or other
direction.
Fig. 7 shows another modification in connecting string c to the segment lever b.
In this case two hygroscopic strings c are used; one end of each string is fastened
to opposite sides of a disc or arms of lever b, whilst the other ends of the
strings, which are guided over rollers d, d', are fastened to the ends of the Bourdon
ring H!.
Instead of fastening the Bourdon ring H' in the middle part to the frame or
foundation of the instrument, as is shown in Figs. 5 to 7, one end of the ring may
be fastened, in which case only the other end of the ring is moveable and can
follow the influences of the air pressure. This construction, which is shown in
Figs. 8, 9, and 10, allows of fastening the hygroscopic string c to the movable end
of the ring only, between arms t, t', fastened to the movable end of ring H¹ by
means of a set screw e¹ or otherwise. The movements of the free end of ring H¹
resulting from the changes of the air pressure are transported by a lever mechanism b
and gearing, or by any other well known mechanical appliance, to hand z of the
instrument, whilst the changes of the length of the hygroscopic string, resulting
from the changes of relative moisture, are at same time and in addition transported
to these movements, as will be understood by reference to Figs. 8, 9, and 10 of the
Drawings.
Numerous mechanical modifications of detail parts of the instrument, such, for
example, as the varieties of gearing for transmissions or variations of the casing or
markings of the scales somewhat analogous to those known in the various construc-
tions of gauge apparatus, may be applied in carrying this Invention into effect;
therefore it is not intended to claim the exact apparatuses shown in the Drawings
alone, but what I claim is,-
1. The mechanical appliances of transporting the combined or compensating

page_text: movements of the diaphragm of an aneroid box or of the movements of a Bourdon
or other aneroid ring resulting from the changes of the air pressure and the
alterations in length of a hygroscopic string resulting from the changes of the
relative moisture of the air to one and the same indicating hand of an instrument
for practical meteorology, constructed and operating substantially as and for the
purpose herein set forth and illustrated by the respective Figures of the accompanying
Sheet of Drawings, and,
2. The application of a wind scale P¹in combination with the weather scale P of
such instruments for the purpose of taking in account or recording the changes of
the wind during the stages of observations for taking a prognosis of the coming
weather, substantially as herein set forth.
In witness whereof, I, the said Friedrich Hermann Felix Engel, have hereunto
set my hand and seal, this Seventeenth day of June, in the year of our
Lord One thousand eight hundred and eighty-one.