An Improvement in or connected with Calipers.
Year: 1889

page_text: UBTLEIE SPECIFICATION.
An Improvement in or connected with Calipers.
1, HENRY BROWN of 24 Clifford Street, Byker, Newcastle on Tyne in the county
of Northumberland, Fitter do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following stateinent :-
This invention relates to an improvement in or connected with calipers and
consists in an improved device for facilitating the accurate reading of measure-
ments whether taken on convex or concave surfaces by calipers. I will now fully
describe my invention with reference to the accompanying drawings in which
Figs. 1 and 2 are elevations showing the calipers closed and open respectively,
Figs. 3 and being plans of Figs. 1 and 2 respectively. Fig. 5 is a section on
line A B in Figs. I and 2. Like letters of reference in the specification indicate
like parts in the drawings. Referring to the latter a a' are the caliper legs
pivotted at a² in the usual way. a is a scale plate the lugged end at of which
is pivotted to upper end of a while the lugged end a of the vernier plate a is
pivotted in like manner to the upper end of a. The upper edge a of scale plate a³
is bevelled to take the corresponding overlapping edge of the vernier plate, the
lower edge of which is formed square so as to take a spring key as as shown most
clearly in section in Fig. 5. By the above described method of construction the
scale plate and vernier can be swung downwards into the very convenient position
shown in Fig. 1 when not required for use, and when required for use the operator
first swings out the scale plate and with it the vernier plate as indicated by the
radial dotted line and arrow in Fig. 1 until these parts are at or nearly at right
angles to the position in which they are shown in Fig. 1 when the calipers can
be used in the ordinary way, the measurements being registered on the primary
and vernier scales to any required degree of nicety. It is obvious from this mode
of construction that according as the caliper legs are moved their contained distance
will be registered on the graduated scale plate and vernier the latter by its con-
nection to the leg a as above described ensuring coincident movement.
If thought necessary, a microscope may be arranged upon the vernier so as to
facilitate the reading thereof in the usual way and if found desirable the move-
ments of the calipers hitherto performed by hand may be operated by screw
motions arranged in any known convenient way to ensure greater precision of
observation.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the saune is to be performed 1 declare that what I
claim is:
1. The combination with calipers « a¹ of a scale plate a³ one end of which has
a lng a pivotted to the upper end of one of the caliper legs, the upper end of
the other caliper leg being similarly attached to a lug formed on the vernier plate
embracing the scale plate substantially as set forth.
2. The arrangement and combination of parts constituting the improvement in
calipers substantially as herein described and illustrated.
A. CRAWHALL CHAPMAN,
2, St. Nicholas Buildings, Newcastle-on-Tyne, Patent Agent for Applicant.