Improvements in Scale Rules or Measures for Computing the Mean Pressures Indicated by Indicator Diagrams or the Mean Width of the like Irregular Figures.
Year: 1889

page_text: Date of Application, 9th Apr., 1889
Complete Specification Left, 9th Jan., 1890-Accepted, 15th Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in Scale Rules or Measures for Computing the Mean
Pressures Indicated by Indicator Diagrams or the Mean Width
of the like Irregular Figures.
We, THOMAS GREY BARRON, of 2, Fern Villas, Elwick Road, and JAMES COOPER
HARDING, of 9, Alderson Street, both of West Hartlepool, in the County of Durham,
Marine Superintending Engineer and Marine Engineering Draughtsman respectively,
do hereby declare the nature of this invention to be as follows:-
-
Our Invention relates to scale rules or measures of the kind employed for com-
puting the mean length of the ordinates of irregular figures, and is more particularly
applicable for ascertaining therefrom the mean pressure indicated by indicator
diagrams, but may also be employed for computing the mean width of the like
irregular figures generally when ascertained by the well known mode of measuring off
a system of ordinates.
The object of our invention is to construct and mark off scale rules or measures
in such a manner that the point reached on the scale by a moveable index following
the result of measuring all the ordinates in succession indicates without further
calculation the mean pressure represented by the figure in question in the case of
indicator diagrams or the mean width of the like irregular figures from which the
area may be readily ascertained.
We will now describe how we apply our invention to the construction and marking
off of scale rules or measures for computing pressures indicated by indicator diagrams,
from which it will be readily understood how our improved scale rules or measures
should be marked off to compute the mean widths of other irregular figures from
which to ascertain their areas. The particular marking employed is capable of
variation or modification in each scale according to its intended use without departing
from the nature of our invention so long as the essential features of our improved
system of marking off each scalo are adhered to. To ascertain the mean pressure
represented by an indicator diagram by the ordinary method, each ordinate is
measured separately by a scale rule marked off to correspond to the pressure
required to deflect the spring, that is, the rule which must be long enough to
measure the longest ordinate of the diagram in question is marked off into the same
number of divisions per inch as the number of lbs. pressure required to deflect the
spring one inch, these being the relative units of length and pressure. The result
of such measurements after being added together are divided by the number of
ordinates employed in order to obtain the mean quantity of pressure represented
by the diagram, that is, if 10 ordinates are used for measuring the indicator diagram
the sum of the measures of the ordinates as taken by the ordinary scale would be
10 times greater than the mean pressure represented by the diagram, or if the number
of ordinates were say 15, then the result obtained from the scale would require to be
divided by 15, and so on for any other number.
An indicator scale rule marked off according to our invention, instead of containing
as many divisions per inch as the number of lbs. pressure corresponding to an inch
deflection in the indicator spring, would only contain as many divisions per inch as
this given number of lbs. of the diagram in question when divided by the number of
ordinates to be measured; as for instance, if the pressure required to deflect the
spring one inch be 30 lbs., and the number of ordinates to be measured be 10, in the
place of the 30 divisions to the inch marked off on an ordinary pressure scale, we only
mark off 3 divisions with corresponding sub-divisions for measuring fractions, so that
when the ordinates are all measured in succession the result reached on our improved
scale corresponds without further calculation with the mean pressure indicated by the

page_text: diagram in question. It is evident that indicator scale rules marked off in the herein-
before described manner with only one scale of divisions could only be employed for
measuring diagrams traced out by the particular indicator which corresponded to the
said scale of divisions marked off, it is also evident that our system of marking
indicator scale rules admits of unlimited variety as to the scale of divisions
marked off.
In order to produce indicator scale rules. which combine with handy dimensions
and a convenient arrangement of parts a variety of scales of divisions marked
thereon and selected with reference to rendering the instrument as serviceable as
possible for its intended purpose, we prefer to construct our indicator scale rules as
follows the scale rule or measure is constructed of such material as is usually
employed for measuring instruments or the like kind such as wood, ivory, metal, or
the like materials whether used singly or in combination and are made to any
convenient dimensions; an index is attached to the scale rule in a suitable way so
that as the rule is applied to each ordinate the index is moved to the position
corresponding to the length of the ordinate measured, and is similarly moved on from
this point to another at which its position marks off the sum of the lengths of the
two ordinates already measured, and so on until the position is reached which
corresponds to the sum of the lengths of all the ordinates of the diagram. This
index may be designed or constructed in any suitable manner, such as a metallic band
or strap, the motion of the index being rendered true by tongues or tenons on the
index fitting into corresponding grooves recessed in the sides or edges of the scale rule.
The index is retained in any required position by a spring or other suitable device fitted
to the index to act upon the scale rule; any device will serve this purpose which
may be relied on to retain the index in any given position when required, whilst
allowing the index to be moved freely along the scale rule for the purpose of taking
measurement.
The whole surface of the scale rule is of course available for marking off a table
of scales of different divisions, each scale of division extending longitudinally along
the face or edge of the scale rule; where the scale is made of sufficient width we
prefer in some cases to provide a slide piece fitted into a groove along the centre of
the rule so as to be used as an extension of the main rule, or for providing extra
surface for marking off scales of divisions, or to be marked or inscribed for the
purpose of calculation. In order to guide the eye to the scale of divisions required
for the particular diagram to be measured, the index is marked with reference figures
so as to serve as a key to all the scales marked on the scale rule, each figure on the
index indicating to what class of diagrams a particular scale of divisions on the scale
rule is applicable. The mode of constructing and marking off a scale rule to measure
the mean widths of irregular figures is similar to that employed for indicator diagrams
and requires no further explanation.
It is of course obvious that the herein before described mode of marking off the
scales to suit the inch as the unit of length and the lb. as the unit of pressure can be
readily transposed to suit other units of length and pressure; such for instance as the
French Standard.
COMPLETE SPECIFICATION.
Improvements in Scale Rules or Measures for Computing 'the Mean
Pressures Indicated by Indicator Diagrams or the Mean Width
of the like Irregular Figures.
We,
THOMAS GREY BARRON, of 2 Fern Villas, Elwick Road; and JAMES COOPER
HARDING, of 9, Alderson Street, both of West Hartlepool, in the County of Durham,
Marine Superintending Engineer, and Marine Engineering Draughtsman; respectively,
do hereby declare the nature of this invention and in what manner the same is to

page_text: be performed, to be particularly described and ascertained in and by the following
statement:-
Our Invention relates to scale rules or measuring instruments of the kind employed
for computing the mean length of the ordinates of irregular figures, and is particularly
applicable to the use and construction of meanometers for ascertaining the meau
pressure represented by the indicator diagrams of steam engines or the like pressure
diagrams, in which the mean length of the ordinates represents the mean pressure
indicated by the diagram; our invention is also applicable to meanometers to be
employed for computing the mean width of irregular figures by the well known mode
of measuring off ordinates from which to compute the area of such irregular figures
or to compute some value or quantity which the series of ordinates have been drawn
to represent such as a daily consumption of coal, the cost of materials, or the like and
similar purposes.
The principal object of our invention is to construct and mark off scale rules or
measuring instruments of the meanometer type and to inscribe a table of scales
consisting of lines or figures thereon so arranged and calculated that from the line
and corresponding figure of the said table of scales reached by sliding a moveable
index pointer or marker from a selected starting point along a succession of distances
corresponding to the several lengths of the ordinates measured may be read off
without further calculation, the mean length of the ordinates thereby avoiding the
more tedious and less accurate method of measuring off and recording the length of
each ordinate separately, which results have to be added together and divided by the
number of the said ordinates to obtain their mean length. Further objects of our
invention are to include on the marking of our improved scale rule one or more scales
for setting off the ordinates of the diagram or other irregular figure in addition to the
table of scales for computing mean lengths of ordinates and if preferred to provide in
the face of the scale rule a slide piece which may be inscribed with additional tables
of scales or be used as a calculating rule adapted to calculations relating to the
purpose for which the scale rule is designed. A further improvement in detail
consists in specially constructing the index pointer or marker to afford a sight of the
line and corresponding figure of the scale next in advance of the position of its
marking edge, so that when the position of the marking edge comes between the two
consecutive division lines the fractional part of the division to be included in the
computation by judgment can be more accurately ascertained.
The several improvements above enumerated we attain substantially as hereinafter
described with reference to the accompanying drawings, in which Figure 1 is a
pressure diagram scale rule with the index pointer in position thereon; Figure 2 is a
transverse sectional view of Figure 1 showing the tongue and groove mode of
attaching the index marker to the scale rule to enable it to slide to any required
position. Figure 3 illustrates a suitable joint for doubling up the scale rule, and
Figure 4a transverse sectional view of a hinged scale rule showing the modified form
of the index marker to prevent it from fouling the hinge; Figures 5, 6 and 7
illustrate in detail the spring employed to restrain the index marker from sliding too
easily along the scale rule; Figures 8 and 9 illustrate in sectional views modifications
of our scale rule by which a sliding piece is inserted in the grooved face of the scale
rule to be used if preferred as a calculating rule, or a paper sheet or metal strip
inscribed with a table of scales is placed in the recess as a cheaper mode of marking
off the table of scales. Figure 10 illustrates the modified index pointer with a
tongued edge the spaces between the tongues of which enable the division line of the
scale next in advance of the position of the marker to be sighted; Figure 11
illustrates a specially constructed index marker or pointer furnished with an arm
projecting therefrom to extend its marking edge a sufficient distance over the diagram
or figure to set off the ordinates from the atmospheric or other datum line. Figure 12
shows how the under side of our scale rule may be utilized by marking thereon the
short scales before referred to as being used in the present system of measuring off
and recording each ordinate separately, but forms no part of our invention, and may
therefore be inscribed on the underside of our scales as shown or be omitted therefrom

page_text: as preferred; Figure 13 is a sectional part of a scale rule inscribed with a table of
scales for computing areas of irregular figures from their mean widths.
It will be observed that the scale rules as illustrated in Figures 1 and 13 are
inscribed with a scale of divisions arranged transversely at the left hand end corre-
sponding to which division lines longitudinal lines run parallel along the full length
of the scale rule and are equally divided throughout their length by intersecting
division lines. Each of these longitudinal lines is a separate scale and the system of
computing from these scales is as follows: taking Figure 1 as an example of a
pressure diagram scale rule worked out to suit the inch as the unit of length and the lb.
as the unit of pressure and 10 as the number of ordinates set off in the diagram, the
figures 8, 16, 32, 64 &c. arranged transversely at the left hand end of the scale rule
indicate the number of lbs. pressure required to deflect the tracing point one inch of
the particular indicator for which the scale on the corresponding longitudinal line is
calculated, thus taking the line marked 8 the scale of divisions set off on the corre-
sponding longitudinal line are calculated for computing from an indicator with a
spring which deflects the tracing point one inch to a pressure of 8 lbs. and so on with the
other numbers of the pressure scale, the corresponding longitudinal scales being long
enough to take in the added up lengths of the ten ordinates and are marked into
divisions as follows; instead of dividing each longitudinal line into as many divisions
per inch as the number of lbs. corresponding to an inch deflection in the indicator
tracing point, each principal division of the longitudinal scale equals 10 times this
number of divisions, as for instance if the pressure required to deflect the indicator
tracing point one inch be 30 lbs. with 10 ordinates to the diagram, in place of the
30 divisions to the inch marked off on an ordinary pressure scale we only mark off
3 principal divisions per inch of length, with corresponding sub-divisions for
measuring fractions, so that taking line a as the starting point of the index marker b
and the edge a' of the index marker as the marking edge the ordinates are
measured off in succession along the longitudinal line by applying the line a to one
extremity of the first ordinate and sliding along the index marker to the other
extremity and then applying the marking edge a¹ to one extremity of the second
ordinate and again sliding the index marker along to the other extremity as before
until all the ordinates are measured when the number on the longitudinal scale plus
any fractional part of the next division gives the mean pressure of the diagram in
question; the marker is preferably marked off transversely with a pressure scale to
aid the eye to select the required longitudinal scale from the right hand end.
In the case of Figure 18 which illustrates a scale rule for computing mean widths
of diagrams or other irregular figures a transverse scale is similarly marked off at the
left hand end representing the scale of inches to the foot to which the figures in
question are drawn such as 1 inch,,, &c. inch to the foot, each transverse
divisional line having its corresponding longitudinal line set off in divisions with each
principal division representing the scale of inches to the foot multiplied by the
number of ordinates with sub-divisions for measuring fractions; thus taking the
scale which is set off to measure one inch to the foot, with 10 as the number of
ordinates instead of having 12 divisions to the inch as in an ordinary scale rule
each principal division equals 1 of an inch, so that the figure on the scale opposite
the position of the index marker after measuring the ordinates in succession plus any
fractional part to be added gives their mean length from which the area of the figure
may be computed.
In order to enable our improved scale rules to be employed in setting off the
ordinates of the diagram or other figure to be measured, we mark off one or more
suitable scales of divisions along that part of the edge c below the groove d which
receives the tongue or pin of the index marker, these divisions may be anything
required but will usually equal 15 of 5 inches, 5" or 4 inches as the case may be,
there being found most frequently used in spacing the ordinates of indicator
diagrams of the usual dimensions, but any other scale of divisions can of course be
substituted. The whole surface of the scale rule is available for marking off as many
differently divided scales as there is space for, each scale extending longitudinally

page_text: along the face or edge of the scale rule; but where the scale rule is made of sufficient
width we prefer in some cases to provide a slide piece fitted into a groove along the
centre of the rule as clearly shown in Figure 8, in which e is the slide piece so let
in, this slide piece may be used as an extension of the main rule or for providing
extra surface for marking off scales by marking its underside, but we prefer to use it
as a calculating rule adapted to the calculations relating to the purpose for which the
scale is designed, as for instance in the case of pressure diagram scale rules, this slide
piece is adapted to calculate from the mean pressure of the diagram of a steam
engine for instance the total borse-power the engine gives out in a
time and similarly for other purposes. In Figure 9, is a strip of card board or
sheet metal with longitudinal scales inscribed on it as a cheaper way of constructing
a rule than by inscribing the table of scales on the wood or other material of which
the rule is composed.
•
given unit of
The index marker a may either be constructed as illustrated in the figures or may
be of any suitable design and arrangement to effect its purpose. In Figure 1 it is
shown with a continuous marking edge a¹, but we prefer to modify this by a
tongued edge for the purpose of exposing the division line of the scale next in
advance of marking edge a', the positions of one edge of each tongue corresponding
to a longitudinal scale line of the rule as clearly shown in Figure 10.
We do not restrict ourselves to the precise tables of scales or details of construction
or marking off of scale rules we have described with reference to the accompanying
drawings which are merely intended to illustrate the essential features of our
invention as the mode of marking off the scales to suit the inch as the unit of length
and the lb. as the unit of pressure in the case of pressure diagram scales or so many
inches to the foot as the scale of measure for computing mean widths and 10 as the
number of ordinates can be readily transposed to suit other units of measure such as
the French Standards and any other number of ordinates may be substituted for 10
the units of measurement and the number of ordinates to the figure being capable of
being varied indefinitely without departing from the nature of our invention.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
:-
Firstly In scale rules or measuring instruments of the meanometer type the
use of a table of scales for computing the mean lengths of the ordinates of pressure
diagrams or other irreguluar figures so marked off transversely and longitudinally
with a table of scales that the mean length of the ordinates can be read off at sight
from the position of an index marker, substantially in the manner and for the purposes
as herein before described and illustrated by way of examples in the accompanying
drawings.
Secondly: The combination of the sliding piece e, with our improved scale
rule or measuring instrument as hereinbefore described and illustrated in Figure 8.
Thirdly-The use and construction of the index marker with a tongued
marking edge as and for the purpose as hereinbefore described and illustrated in
Figure 10.
كيم
G. J. CLARKSON,
Stockton-on-Tees, Agent for the Applicants.