IMPROVEMENTS IN CALIPERS AND DIVIDERS
Year: 1885

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I, HERBERT JOHN ALLISON, of the firm of Allison Brothers, Patent Agents, of
52 Chancery Lane, London, in the County of Middlesex, do hereby declare the
nature of my invention for "IMPROVEMENTS IN CALIPERS AND DIVIDERS," which
invention has been communicated to me from abroad by Charles Pease Fay, of
Springfield, Massachusetts, United States of America, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
This invention relates to calipers and dividers of the class in which the legs are
pressed toward or from each other by a spring. The invention has for its object to
provide a simple and cheap construction whereby the legs may be readily separated
from each other and from the spring, so that different legs may be used inter-
changeably, and also to enable the spring to exert a practically uniform pressure on
the legs without regard to the distance to which they are opened.
To these ends my invention consists in the improvements which I will now
proceed to describe.
Of the accompanying drawings forming a part of this specification, Figure 1
represents a side elevation of a pair of calipers provided with my improvements.
Figure 2 represents a section on line x x Figure 1. Figure 3 represents a section
on line y y Figure 2. Figure 4 represents a side elevation of a modification.
Figure 5 represents a side view of a detached leg. Figure 6 represents a view
of the piece from which the spring is made.
The same letters of reference indicate the same parts in all the figures.
In the drawings, a a represent the legs which may be of any of the forms used in
calipers or dividers. In the inner side of the upper ends of the legs a, a, are
formed sockets b, b, which fit the opposite sides of a pivot or fulcrum pin c,
interposed between the legs. Said pin has a head at each end as shown in
Figure 2, said head bearing against the sides of the legs. The backs of the legs
are provided with notches d, d, which receive the ends of the bow spring e.
spring is made by bending a flat piece of steel of the form shown in Figure 6 into
nearly a complete circle, 'the ends of the piece being notched to form shoulders, e¹ e¹,
Price I
Said

page_text: which project over the sides of the legs as shown in Figures 1 and 3, and thus
keep the spring in place laterally. The ends of the spring press inwardly against
the legs and hold them against the pin c. When the notches d, d, are above the
pin as shown in Figures 1, 2, 3, and 5, the inward pressure of the spring against
the legs tends to spread or separate the main portions of the legs so that the
retaining nut, g, on the screw h, must be placed so as to resist the separation of
the legs as shown in Figure, 1, the screw being pivoted at i, to one leg, and being
non rotating, while the nut bears against the other and is rotated on the screw.
When the notches d, d, are below the pin c, as shown in Figure 4, the pressure of
the spring tends to close the legs, so that the nut g, requires to be placed so as to
resist the closing movement. In this case the screw adapted to turn freely in
both legs and in the nut. The ends of the spring are in either case so near the
pin c, that the spring is not sufficiently expanded or contracted by the opening or
closing of the legs to make any material variation in its pressure or tension, hence
said pressure is practically uniform.
The legs may be separated from each other and from the spring by first opening
the legs to their fullest extent, so as to extend the spring, then placing any suitable
rigid obstruction within the spring to prevent it from contracting, and then closing
the legs, so that their notched sides can pass out between the ends of the extended
spring. The legs have no positive connection with the pin c, so that when they
are removed from the spring they readily separate from each other and from the
pin. Different legs can therefore be used interchangeably.
To connect the legs and spring, place the notched ends of the legs between the
ends of the spring and remove the obstruction that holds the spring expanded when
the ends of the spring will again bear upon and hold the legs.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
First. The improved calipers or dividers composed of the separable legs, the
double headed fulcrum pin interposed between the proximate sides of the legs and
fitting in sockets formed in the legs, the bow spring engaged at its ends with
notches formed in the outer sides of the legs, either above or below the fulcrum
pin, and the screw with its retaining nut, as set forth.
Second. In calipers & dividers the use of the curved spring substantially as
described engaging with the legs either above or below the fulcrum pin the legs
being provided with any suitable adjusting device.
"
Dated the and do of Tunn 100K