IMPROVEMENTS IN WIRE GUAGES
Year: 1885

page_text: I ALEXANDER PELHAM TROTTER, of 7 Furnivals Inn, London, in the County
of Middlesex, Civil Engineer, do hereby declare the nature of my Invention for
" IMPROVEMENTS IN WIRE GUAGES" to be as follows:-
This invention relates to the construction of a wire gauge whereby minute
measurements may be effected-for instance the exact thickness or diameter of
wire in accordance with the Board of Trade standard guage or the thickness of
sheet metal.or other material ascertained in "mils" (or thousandths of an inch) or
in decimals of a millimetre and consists of a metallic plate by preference milled
at the edges for convenience in holding. In the centre of this plate is fitted a slide
which at one extremity is widened out to the same width as the outer plate and at
the other end is provided with an eye. The corresponding edges of the plate and
of the slide are suitably graduated for instance the lower edge of the plate is
divided into equal divisions and numbered from 6 to 40 corresponding to the
Board of Trade standard wire-gauge and the lower edge of the slide is similarly
marked but at a vernier scale.
In order to use this instrument it is only necessary to insert and nip the wire or
other article requiring to be measured between the jaws or openings formed by the
extremity of the slide and the widened out portion of the plate and then the
measure or gauge of thickness is ascertained by observing the numbers of the corre
sponding graduations which coincide upon both scales-such numbers constituting
the measurement required.
In this manner am enabled to construct a sliding vernier calliper gauge of
several standard scales such as the inch and the centimetre provided severally
with verniers whereby minute measurements may be effected with or without the
use of a screw.
On the back of the guage is also arranged a scale by which the areas of circles
whose diameters are nipped between the jaws may be approximately measured in
thousandths of a square inch.
JOHN G. WILSON,
Agent for the Applicant.

page_text: I ALEXANDER PELHAM TROTTER, of 7 Furnivals Inn, Holborn, in the County
of Middlesex, Civil Engineer, do hereby declare the nature of my invention 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 the construction of a wire guage whereby minute
measurements may be effected for instance the exact thickness or diameter of
wire in accordance with the Board of Trade standard guage or the thickness of
sheet metal or other material ascertained in "mils" (or thousandths of an inch) or
in decimals of a millimetre...
On the accompanying drawing Fig. 1. is a front view and Fig. 2. a back view
of my improved wire gauge drawn about three times full size.
The gauge consists of a metallic plate a by preference milled at the edges for
convenience in holding. In the centre of this plate is fitted a slide 6 which at one
extremity is widened out to the same width as the outer plate and at the other
end is provided with an eye c. The corresponding edges of the plate and of the
slide are suitably graduated for instance the lower edge of the plate is divided into
equal divisions and numbered from 6 to 40 corresponding to the Board of Trade
standard wire gauge and the lower edge of the slide is similarly marked but as a
vernier scale.
In order to use this instrument it is only necessary to insert and nip the wire or
other article requiring to be measured between the jaws or openings formed by the
extremity of the slide and the widened out portion of the plate and then the
measure or guage of thickness is ascertained by observing the numbers of the corre-
sponding graduations which coincide upon both scales-such numbers constituting
the measurement required.
This S. W. G. (standard wire guage) vernier is a peculiar one, and is read by
observing the numbers of the graduations which coincide, the two numbers being
identical. For instance, if a well worn penny be nipped between the jaws it will
be found that the graduation between 16 and 20, that is 18, will be opposite the
corresponding graduation; the thickness is therefore 18 S. W. G. A new penny
will in the same way measure about 16 S. W. G. and with a slightly worn penny
neither 16 nor 18 will coincide, but it will be found that the half length graduation
corresponding to 17 on the slide, will be in more or less accurate correspondence
with its fellow on the body, and the reading will be 16, 17, or 171, as the case
may be.
Other examples could be given, but these will serve to show the use and value of
the gauge as against present methods of computation, as all the measurements made
by it can be relied upon for absolute correctness.
The two other verniers on the opposite edge are graduated in decimals of an
inch, by which the reading may be taken in "mils" (or thousandths of an inch) or
in decimals of a millimetre. The verniers for accurate measurements should be
read by lens.

page_text: Each has two scales, one with an arrow head and one without. The latter is
the scale proper, the former is the vernier. The arrow head points to the
graduation on the scale from which the approximate reading is taken. The first
decimal figure is read on the scale by the direct indication of the arrow head.
It will be found that one of the graduations of the scale and the following
figures of the reading are the numbers which correspond to this graduation, the
numbers counting from the arrow head.
On the back of the guage is a scale by which the areas of circles, whose
diameters are nipped between the jaws, may be approximately measured in
thousandths of a square inch. From this scale may be computed the capacity
of high conductivity copper wire for carrying an electric current by any of the
well known formulae.
The carrying capacity of the copper wire or an armature or magnet may be
found at once by multiplying the coefficient applicable to the particular case.
The area as read on guage in thousandths (not in square inches) multiplied
by 0-386 gives the weight in pounds of a length of a 100 feet or multiplied by 12
gives the length in feet of pure copper wire having a resistance of one tenth of
an ohm.
In this manner I am enabled to construct a sliding vernier calliper guage of
several standard scales such as the inch and the centimetre provided severally
with verniers whereby minute measurement may be effected with or without the
use of a screw.
Having thus particularly described and ascertained the nature of my invention
I declare that what I claim is
The improved construction and arrangement of wire guage marked with various
scales of diameters and areas and arbitrary gauges and the application thereto of
verniers whereby minute measurement may be effected substantially as herein-
before described.
Dated this 27th day of October 1885