IMPROVEMENTS IN CALLIPERS
Year: 1883

page_text: LETTERS PATENT to Saint John Vincent Day of 115 St Vincent Street,
Glasgow in the County of Lanark North Britain, Civil Engineer and Patent
Agent, for an Invention of "IMPROVEMENTS IN CALLIPERS" a communication
to him from abroad by Andrew Nimmo of Bristol; in the State of Rhode
Island in the United States of America
PROVISIONAL SPECIFICATION left by the said Saint John Vincent Day at
the Office of the Commissioners of Patents on the 16th May 1883.
SAINT JOHN VINCENT DAY, of 115 St Vincent Street, Glasgow in the County
of Lanark, North Britain, Civil Engineer and Patent Agent, "IMPROVEMENTS
IN CALLIPERS" [a communication to him from abroad by Andrew Nimmo of
Bristol, in the State of Rhode Island in the United States of America]
This Invention which relates to improvements in Callipers has for its object to
facilitate the measurement of diameter, circumference, area, cubical contents, weight
and other measurements of spherical, cylindrical, (either hollow or solid) and other
shaped bodies and also the measuring of the surfaces of spherical, cylindrical,
conical and other shaped bodies.
In carrying this invention into practice there are provided two pivoted curved
legs as in ordinary outside callipers, at the free ends of which, elongations are
formed, the inner edges of which meet when closed and are radial to the axis upon
which the legs pivot.-The distance from the axis of the callipers to the extreme
outer points of the elongations is in the same proportion to the distance from the
axis to the inner extreme points of the elongations, as the circumference of a circle
is to its diameter, so that the circumference of a circle whose diameter is measured
by the inner points of the elongations is indicated by the distance between the
outer points of the same.-The fractional parts of the circumference of the circle
are or may be marked along the elongations, or the elongations may be of the
required length to measure off any fractional part of the circumference of the circle
at the extreme outer points of the said elongations.
By means of the callipers with the longer elongations hereinbefore mentioned,

page_text: the surfaces of spheres may be reduced to equal rectangles by measuring the
diameter of the sphere between the inner points of the elongations, which
measurement will represent the base while the distance between the outer points
will represent the altitude of a rectangle equal to the surface of the sphere thus
measured, and the distance between the outer points of the shorter elongations 5
when used for the same purpose will represent half the surface of the sphere.
The convex surface of a cylinder may be measured by taking by the callipers
the circumference of the base as herein before described and the height of cylinder
for height of the rectangle equal in area to the convex surface of the cylinder.
Other measurements may be obtained by applying the improved callipers in a
manner corresponding to the forms to be measured.-A notch or notches may be
formed on the inner edge of the elongations the edge of which notch or notches
nearest to the axis is or are in proportion to the diameter of the circle measured
by the inner points of the elongations.-The cubical contents of a sphere may be
ascertained in terms of a flat bar of equal capacity, by taking the diameter of the
sphere between the inner points which will give the length while the distance
between the inner edges of a notch in the necessary position gives a third of the
circumference as the width and the radius of the sphere will be the thickness of a
flat bar equal in cubical content to that of the sphere.
Another form of callipers constructed according to this invention consists of the
elongations being formed near the axis while the curved legs of the same are
distant from it, at the ends of these legs a short shank is formed and which by
measuring the diameter of a circle between the inner points of this short shank,
represents the third or other fractional part of the circumference of the circle so
measured. The elongations near the axis are marked off to indicate smaller
fractional parts and the number of degrees contained in these parts of the
circumference and any divisions necessary for computing other measurements
may be marked on one or both sides of these elongations.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Saint John Vincent Day in the Great Seal Patent Office on the
16th November 1883.
SAINT JOHN VINCENT DAY of 115 Saint Vincent Street; Glasgow, in the County
of Lanark, North Britain, Civil Engineer and Patent Agent "IMPROVEMENTS IN
CALLIPERS "A communication to me from abroad by Andrew' Nimmo of Bristol
in the state of Rhode Island, in the United States of America
This invention which relates to improvements in Callipers has for its object to
facilitate the measurement of diameter, circumference, area, cubical contents, weight
and other measurements of spherical, cylindrical, (either hollow or solid) and other
shaped bodies and also the measuring of the surfaces of spherical, cylindrical,
conical and other shaped bodies.
In carrying this invention into practice there are provided two pivoted curved
legs as in ordinary outside callipers, at the free ends of which, elongations are
formed, the inner edges of which meet when closed and are radial to the axis upon
which the legs pivot. The distance from the axis of the callipers to the extreme
outer points of the elongations is in the same proportion to the distance from the
axis to the inner extreme points of the elongations, as the circumference of a circle
is to its diameter, so that the circumference of a circle whose diameter is measured
by the inner points of the elongations is indicated by the distance between the
outer points of the same. The fractional parts of the circumference of the circle
are or may be marked along the elongations, or the elongations may be of the
required length to measure off any fractional part of the circumference of the circle
at the extreme outer points of the said elongations.
:
By means of the callipers with the longer elongations herein before mentioned,
the surfaces of spheres may be reduced to equal rectangles by measuring the
diameter of the sphere between the inner points of the elongations, which
measurement will represent the base while the distance between the outer points
will represent the altitude of a rectangle equal to the surface of the sphere thus
measured, and in cases where shorter elongations are used the distance between the
outer points of such shorter elongations will represent half or other fractional
portion of the surface of the sphere corresponding to the extent of the elongations.
The convex surface of a cylinder may be measured by taking by the callipers
the circumference of the base as hereinbefore described and the height of cylinder
for height of the rectangle equal in area to the convex surface of the cylinder.
Other measurements may be obtained by applying the improved callipers in a
manner corresponding to the forms to be measured. A notch or notches is or may
at any proportional or fractional distances be formed on the inner edge of the
elongations the distance between the edges of such notch or notches nearest to
the axis gives the fractional proportions corresponding to the diameter of the circle
measured by the inner points of the elongations. The cubical contents of a sphere
may be ascertained in terms of a flat bar of equal capacity, by taking the diameter
of the sphere between the inner points of the elongations which will give the
length, while the distance between the inner edges of a notch in the necessary
position gives a third of the circumference as the width, and the radius of the
sphere will be the thickness of a flat bar equal in cubical content to that of the
sphere.
Another form of callipers constructed according to this invention consists of the
elongations being formed near the axis while the curved legs of the same, are
distant from it, at the ends of these legs a short shank is formed and which by

page_text: measuring the diameter of a circle between the inner points of this short shank,
represents the third or other fractional part of the circumference of the circle so
measured. The elongations near the axis. are marked off to indicate smaller
fractional parts and the number of degrees contained in these parts of the
circumference and any divisions necessary for computing other measurements may
be marked on one or both sides of these elongations.
I
And in order that the said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, reference being had to
the accompanying Drawings and to the letters and Figures marked thereon that
is to say
'
Figure is a plan of the improved callipers for ascertaining the diameter,
circumference, cubical contents, weight and other measurements of spherical,
cylindrical (either hollow or solid) and other shaped bodies.
Figure 2 is a plan of that side of the same opposite to Figure 1.
Figure 3 is a plan of a modification of the same.
Figure 4 is a plan of the same instrument represented as in use for ascertaining
a measurement.
Figures 5, 6, 7 and 8 are plans of modified forms of the improved callipers,
the views at Figures 6 and 7 being plans of opposite sides of the same
instrument.
-
The callipers represented at Figures 1 to 4 are formed of the two semicircular
or segmental pieces a, which are pivoted to each other, so that they can swing in
parallel planes, in the same manner as ordinary callipers. On the free ends of the
pieces a, the shanks 6 are formed, which have a greater or less length, the inner or
adjoining edges of the said shanks being on lines which are radii from the centre
of the pivot c, by which the two pieces a are united to each other. Notches & are
formed in the inner edges of the shanks b at the inner ends of the same, and
notches e are formed in the inner edges of the shanks b, at the outer ends of the
same. The distance between the outer prongs f, formed by the notches e, indicate
the circumference of circular bodies the diameters of which are taken between the
shanks at the prongs g; and the corners h, formed by the notches e, are used to
measure the weight of bars, rods and other bodies of cast iron as hereinafter more
fully described. The shanks b are provided with a scale, which is to be used as a
gauge for measuring the diameter of circular bodies, for obtaining proportions, and
for the purpose of ascertaining the area in square inches of a cross-section of
rectangular bars as represented more particularly at Figure 4. For instance, if
one dimension (say its thickness) of the rectangular bar i, be taken between the
points g, g, the distance between the shanks at the points of the said scales
marking another dimension (say the width) will give the number of square inches
in, or area of, the cross section of the bar i. On the other flat sides of the
shanks b (that is to say the sides opposite to those shewn at Figure 1) as
represented at Figure 2, there are provided the marks j, k, land m, which indicate
the locations for taking the measurements for ascertaining the weights of lead,
cast-brass, steel, and wrought-iron respectively.
The callipers represented at Figure 5. have short tapering shanks, each of which
has a V-shaped notch n in its inner side and near its inner end, which notch has
its sides at an angle of fifty five degrees, so that the notch can be used as a gauge
for grinding the edges on tools, for threading screws, and for similar purposes.
The ends of the shanks b of the callipers represented at Figure 5, are flattened
and pointed and are provided with the transverse mark o which shews three-
eighths circumference of a bar or rod whose diameter is taken between the inner
ends of the shanks b. At the outer ends of these shanks, one half the
circumference is shewn, and at the inner corners p, formed by the notches n,
one-third the circumference is shewn. Other marks as at o, may be provided as
required for shewing other fractions of circumference.
-
The callipers are used in the following manner. If the circumference of a rod

page_text: is to be obtained by means of the Callipers represented at Figures 1 to 4, the
diameter of the rod is taken between the prongs g, g, and the distance between the
prongs ff, will be equal to the circumference. The distance between the corners
h, h, will indicate the weight per linear foot of cast-iron in pounds, on any scale
on which the distance between the prongs g, g, has been set to number corre-
sponding to square inches in cross section. The distance between the inner edges
at the marks j, k, land m-Figure 2-indicates in a similar manner the weight
per half linear foot of lead, cast-brass, steel, or wrought iron respectively. It being
explained that the positions of these marks correspond with and are arranged
proportionally to the specific gravity of the said substances. The callipers
represented at Figure 5, can be used for ascertaining one-third, three-eighths, and
one balf circumferences, and corresponding parts of the area of a circular body, the
diameter of which is taken between the inner ends of the shanks b. If the
diameter of a sphere be taken between the inner ends of the. shanks of these
callipers, one-third of the circumference of the sphere is obtained, and if that is
multiplied with the radius and then with the diameter, the cubical contents of the
sphere is obtained. The weight of a length of tubing can also be ascertained by
means of this instrument, by first ascertaining the weight of a solid cylinder of the
length of the tubing, then ascertaining the weight of a solid cylinder of the size
of the opening in the tube, and substracting the latter from the former, the
difference indicating the weight of the tube. Spherical, cylindrical (either hollow
or solid) and other shaped bodies, by the application of these callipers can be
resolved in terms of equal flat or rectangular bars and then, as herein before
described the area and weight may be obtained. The pressure on a piston, the
quantity of steam in a cylinder can easily be computed by means of these callipers.
As for instance if the diameter of a piston or safety valve be taken between the
corners c¹, c, (Figure 5) and a cypher annexed to the number of square inches
contained in the rectangle measured by the said corners the distance between the
points d', d', gives the total pressure on piston or safety valve when the pressure
per square inch is twenty pounds If the diameter of a piston or safety valve be
taken between the corners g, g, of the callipers represented at Figure 1 and a
cypher annexed to the number of square inches contained in the rectangle measured
by the said corners g, g, the distance between the points f. f, gives the total pressure
on the piston or safety valve when the pressure per square inch is forty pounds.
Or if a cypher be annexed to the product of the multiplication of the distance
between the points f, f, by the distance between the points g, g, the same result
inay be arrived at." The distance between the points f. f, multiplied by the
distance between any sub-division out from f, f, gives total to higher pressures.
The callipers represented at Figures 6 and 7, are those by which one-fifth to
one-fortieth of the circumference of a circular body may be ascertained. It may
be seen in this form of instrument that the longer shanks b, are formed near to the
pivot c, and the two semicircular or segmental pieces a, are formed distant from
the same, while at the extremities of these segmental pieces, the shorter shanks q,
are formed, with their inner or adjoining. edges on radial lines from the centre of
the pivot c. At the outer or extreme points of the shorter shanks q, of these
callipers is indicated, one-third the circumference of any circle whose diameter is
taken between the corners r: r; and the inner edge of the shanks b, b, being on
radial lines, there is marked on one of them a series of numbers representing
fractional parts of the circumference from one-fifth to one-fortieth.-There are also
indicated on the other shank the number of degrees contained in such arcs.-
When a small fractional part of the circumference is required as for example one
four hundredth (400), the corners r, r, are set apart the tenth part of the diameter
and the distance between the shanks b, at the mark 40, indicates the one-four
hundredth part of the circumference.-The areas corresponding to these fractional
parts may also be easily ascertained by multiplying the distance between the
corners r, r, with the width at the place corresponding to four times the required
fractional part. The areas of mixed numbers may also be ascertained by means of
$

page_text: these callipers. By this instrument also the setting out of gear-wheels may be
easily effected. The circumference of gear wheels may be considered to be divided
into as many parts as there are teeth. If therefore the point 61, Figures 5, and 6,
be set to pitch at the part of circumference corresponding to number of teeth, the
corners r, r, will measure the diameter of 'pitch-line correctly if circular pitch be
understood and approximately if chordal pitch be used.
Although the callipers represented at Figures 6, and 7, do not indicate less than
the one-fortieth (40) of circumference, yet by setting the callipers at that part, say
ten times the pitch, the distance between r, r, measures diameter of pitch line for
wheel having 400 teeth and radius of wheel having 800, teeth and so on Marks are
so placed on the side of callipers represented at Figure 7, that when the corners r, r,
are set to pitch the openings at the parts marked 8, t, u, and v, indicate the pro-
portions of teeth, thus the length of opening at 8, indicates the space between the
teeth on pitch line,-at t, the thickness of teeth, at u, the depth from pitch line to
bottom of tooth, and at v, the distance from pitch line to top of tooth.-The callipers
may also be used as an angular gauge the inner edges of the shanks b, b, being on
radial lines with the shorter shanks q, q, the amount of opening at the part marked
will
(which is one tenth of the distance between the axis of the pivot c, and the
corners r, r,) indicates one-tenth of any size taken between the points r, r, thus, if
the corners r, r, be set distant one-tenth of an inch, then the part marked
measure one hundredth of an inch and so on.-If the corners r, r, be set distant
one-quarter of an inch, then the part marked 1 will measure 025 of an inch.-—If
the corners r, r, be set distant one-eighth of an inch, the part marked, will
measure one-sixty-fourth of an inch and so on. On the same principle the
callipers represented at Figure 5, may be used for this purpose and it is obvious
how the multiplication and division of numbers may be effected by means of these
callipers.
The callipers represented at Figure 8, are so formed that any fractional part of a
circumference may be ascertained, the diameter being taken between the
corners w, w. These callipers are provided with the slide x, spring y, and screw
adjustment z, to enable the said adjustment to be effected with greater facility and
the callipers when so adjusted may be secured in position by the tightening of the
binding screw a¹.
Having now described and particularly ascertained the nature of the said
Invention and the system, mode or manner in or under which the same is or may
be used or practically carried into effect it is to be observed in conclusion that
the precise form or detail hereinbefore described with reference to the accompanying
Drawings may be varied without departing from the essential features of the
Invention but what is considered to be novel and original and therefore Claimed
as the Invention secured by the hereinbefore in part recited Letters Patent is :-
First. Callipers consisting of two curved pieces hinged to each other and provided
with shanks projecting from the free ends of the curved pieces, the inner edges of
the said shanks being on radial lines from the centre of the pivot uniting the two
curved pieces substantially as and for the purposes herein before described.
Second Callipers formed of two curved pieces pivoted to each other and
provided with shanks having notches in their inner edges substantially as and for
the purposes herein before set forth with reference to Figures 5, and 8, of the
accompanying Drawings.
Third. Callipers formed of two curved pieces pivoted to each other and provided
with shanks having notches in their inner edges and one or more marks on their
Bides substantially as herein before described with reference to Figures 5, and 8, of
the accompanying Drawings.
Fourth. Callipers formed with two curved pieces pivoted to each other and
having shanks at their free ends, which shanks are provided at the outer and inner
ends with notches substantially as and for the purposes herein before set forth with
reference to Figures 1, 2, 3, and 4, of the accompanying Drawings.
Fifth-Callipers consisting of two curved pieces pivoted to each other and

page_text: .
provided at the free ends with shanks which are provided with the marks j, k, l,
and m, substantially as and for the purposes hereinbefore set forth with reference
more particularly to Figure 2, of the accompanying Drawings.
Sixth. Callipers formed of two curved pieces pivoted to each other and provided
at the free ends with shanks having a graduated scale on one side and the
marks j, k, l, and m, on the opposite side, substantially as and for the purposes
herein before set forth with reference more particularly to Figures 1, 2, 3, and 4, of
the accompanying drawings.
Seventh Callipers formed of two pieces pivoted to each other and provided at
their inner and outer ends with shanks, the inner shanks having graduated scales
on their opposite sides substantially as and for the purposes hereinbefore set forth
with reference to Figures 6, and 7, of the accompanying Drawings.
Eighth Callipers consisting of two pieces hinged to each other provided with
shanks projecting from the free ends with or without the shanks at the inner ends
of the same, the inner edges of the said shanks being on radial lines from the
centre of the uniting pivot, the said shanks being provided with scales for
ascertaining the weights and measurements of spherical, cylindrical (either hollow
or solid) and other shaped bodies from the diameter and cross sectional measure-
ments of said bodies substantially as hereinbefore set forth with reference to the
accompanying Drawings.
In Witness Whereof I the said Saint John Vincent Day have hereunto set my
hand and seal this fourteenth day of November in the year of our Lord One
thousand eight hundred and eighty three.
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