A NEW OR IMPROVED INSTRUMENT FOR EASILY AND ACCU- RATELY MEASURING AND INDICATING THE THICKNESS OR WEIGHT OF SHEET METAL PLATES AND THE SIZES OF OTHER ARTICLES
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by William Paton Buchan at the Office
of the Commissioners of Patents on the 9th May 1879.
WILLIAM PATON BUCHAN, of Glasgow, in the County of Lanark, North Britain,
Sanitary Engineer. "A NEW OR IMPROVED INSTRUMENT FOR EASILY AND ACCU-
RATELY MEASURING AND INDICATING THE THICKNESS OR WEIGHT OF SHEET
METAL PLATES AND THE SIZES OF OTHER ARTICLES."
This Invention has reference to the improved construction of a simple, portable,
or pocket instrument or pair of callipers for instantaneously measuring and
indicating the thickness of sheet metal plates or their weights, and the sizes of
other articles, in a better and more reliable way than with the ordinary gauges,
measuring foot rules, or the making of calculations, which will be of great use to
plumbers, architects, measurers, and others connected with the building trade, and
salesmen, storekeepers, dealers and workers in sheet metal, and mechanics or others
requiring such exact measurements, and will save such persons much time and
trouble as compared with the modes and means heretofore in use for effecting the
said purposes. And the nature and novelty of the Invention, according to one
simple construction of this new or improved instrument, as shown closed up in side
and edge views in Figures 1 and 2, and open as in use in Figure 3, all respectively
on the accompanying Sheet of Drawings, consists as follows:-In forming this
instrument or pair of callipers of two limbs or levers A, A¹, of flat or thin sheet
metal or other suitable material (preferably steel plate), crossing each other at their
joint pin A at a short distance (as from to one inch) from their curved embracing
points a, a, for catching the sheet metal or other article between them, and
touching the surfaces on opposite sides.
The long arms A and A, extending on the opposite side of the fulcrum pin A",
are formed to oscillate close to each other, the one A with index pointers 1, 2, 3,
and 4 formed at different distances along its one edge, and the other with divided
arcs or sectors on its surface under or close in front of these pointers, and marked
1, 2, 3, and 4' to correspond.
The distances of these divided index arcs and pointers from the contre A" are
made any desired multiple of the distance of the embracing points a, a², from this
centre A, as say, 8, 10, 12, and 16 times, so that when the points a, a, are made
to grip a plate or other object as , these several pointers will indicate the thick-
ness on their respective divided arcs 8, 10, 12, and 16 times as great as the real

page_text: size, that is, the thickness of a inch plate 2, as shown in Figure 3, would be indi-
cated by a distance of ", ", ", and 1" inch on these arcs respectively, and these
multiplied arcs may be subdivided to represent eighths, tenths, or other proportional
parts of these.
Thus it will be seen that these arcs may be made any desired proportional
multiple of that made by the catching or actual embracing and sizing points or
jaws a, a, and by taking these arcs to represent any desired aliquot part, as of an
inch (or other standard English or foreign measure), and then subdividing the
multiplied arc into smaller, equal, or proportionate parts, as stated, into tenths and
hundreds, this would form a decimal scale with an index pointer so large and visible
to the eye as to be able to be easily seen (or to set the instrument) to take and
indicate the finest measurements most accurately and proportionately to any desired
standard measure, the importance of which is self evident.
A further improvement has reference to making the instrument also indicate at
a glance the weight of sheet metal, as lead, zinc, brass, or iron, or of other metal,
such as copper or yellow metal used for sheathing ships, in relation or proportion to
their thickness or superficial square measurement, as per square foot or yard; and
consists in making the multiplied proportional parts or arc scales to represent
aliquot parts of the standard weights of the particular metal, as say in pounds,
taken in proportion to its thickness per square foot, or other square measure desired,
as shown in the scale for sheet lead in 1', and then in subdividing these into equal
parts, representing half pounds, quarter pounds, or ounces and grains, or decimals
of pounds if desired, so as thus to be able to take or determine the exact weight of
sheet metals most accurately, as well as their thickness instantly by looking at the
index points and scale after setting or closing the griping points a, a', on the sheet
metal, all as seen and indicated in Figure 3.
The index arc 11 of the pointer 1 alone is shown as divided in aliquot parts of an
inch, representing pounds for sheet lead, marked 1, 2, 3, 4, 5, 6, subdivided into
halves and quarters with the decimal of the thickness of plate per inch indicated in
decimal figures over the pounds.
And it will be understood that the other index arcs marked 21, 3', and 4', for
zinc, brass, and iron, might be divided and marked in an equivalent manner for
taking the thickness or weight of these metals, as described in relation to that
for sheet lead, though not so shown in the Drawings.
These instruments might be made with fewer or more of these pointers and
divided indices to suit other proportions of the sizes and weights of material, as
shown at 5, 5¹, which represents a multiple of four times the actual size of the
article measured by the points a, a, that is, half that indicated by the index 1, 1¹.
This instrument may also when desired be fitted with a retaining screw b and
thumb screw b¹, fixed in one limb, as A¹, and with a slot 6 in the other A, so as to
fix the index points in any position desired or that they may be set to, to retain
any particular size on the calliper points a, a, in use for the time being; or when
the instrment is closed up to prevent the shifting of the limbs when not in use or
for wearing in the pocket. This instrument is shown as fitted at the outer extremity.
of the arms A, A', with a long hinged divided index segment or sector A³, hinged
to the one limb A at a², and passed through its index guide a¹, fixed in the other
limb A', so as to give the largest multiple scale of measurement possible by this
instrument, as say, 18 or 20 times the actual size of the material gauged between
the embracing points a, a¹, thus enabling the aliquot parts of the scale on this
sector A2, which might represent inches, being subdivided decimally or otherwise
into parts large enough to be visibly and easily seen, indicating hundredth or
thousandth parts of an inch, and when the instrument is not in use this divided
arc A²
may be folded down and retained by a spring clip at a³ alongside of its
carrying arm A, as seen in Figure 1.
And, further, that although not shown, each index 11, 21, 31, 4', might be fitted
with a like hinged divided index segment fulcrumed on the back plate or limb A³,

page_text: for giving longer measurements when desired than is possible with the arcs only
divided on the front of the arm A¹, shown at 1', 1'.
And that the embracing points a, a¹, might be fitted with a short adjustable or
hinged griping plate, as for the gauging of softer and thicker articles than sheet
metal, and that although these points have been shown only for the embracing and
taking the thickness of articles, they might be turned outwards and made to gauge
the sizes of holes or tubes, and formed with various lengths of limbs to gauge
smaller or larger articles, and that the limbs might be made thicker and stronger,
or bow shaped instead of straight, as shown in the Drawings, and fitted with a
moving and setting screw, with numbered divisions or an index round it, or on its
fixed washer below for setting and indicating the distance of the griping limbs to
the greatest nicety or smallest accurate measurements by the turning of the screw,
shown by the said divisions.
In some cases this instrument may be constructed with a single multiple scale or
divided arc, as A2, and with its index a² (that is, without the indexes 1, 2, 3, 4,
or 5, or with only one of these instead of the hinged are A2, and their relative
divided enlarged scales) divided decimally, so that on setting the instrument to
guage the size, and taking note of the unit and decimal on the said scale, the weight
of the particular sheet metal or other articles per square foot may be got opposite
that decimal on a table of square weights ranged with or opposite the decimal
index column engraved on one of the limbs A or A' of the instrument; or it might
be from tables in a small book of tables for the purpose, corresponding to and
accompanying the instrument. And when desired this instrument may also be
made a wire gauge by having the ordinary graduated gauge slits and holes formed
in one edge of one of the limbs A or A', as shown at B in Figure 1, each marked
or numbered in the usual manner, cut or stamped on the surface of the plate close
to each gauge slit; and although the limbs A, A', have been shown as crossed at their
joint A, and with the embracing points a, a¹, beyond this, it is to be understood
that the limbs might be jointed at their extreme ends, and have the embracing or
sizing points a, a¹, formed on the inner side, or same side, as the limbs A, A',
nearer to the fulcrum than the indexes and scales as 1, 1', and 2, 21, or others.