IMPROVEMENTS IN INSTRUMENTS FOR MEASURING THICKNESSES OF OBJECTS."
Year: 1880

page_text: LETTERS PATENT to John Milner, of Alderney Street, Pimlico, in the County
of Middlesex, for an Invention of "IMPROVEMENTS IN INSTRUMENTS FOR
MEASURING THICKNESSES OF OBJECTS."
PROVISIONAL SPECIFICATION left by the said John Milner at the Office of
the Commissioners of Patents on the 30th September 1880.
JOHN MILNER, of Alderney Street, Pimlico, in the County of Middlesex.
"IMPROVEMENTS IN INSTRUMENTS FOR MEASURING THICKNESSES OF OBJECTS."
According to my present Invention I construct an instrument for measuring
small thicknesses of objects, such as wire, sheet metal, and the like as follows:-
Two bars are connected together so as to be capable of receiving parallel motion to
and from or upon each other. These bars have parallel gauging faces, between
which the object to be measured is introduced. One of the bars carries a scale, and
the other bar presents a line, either the scale or the line, or both, being inclined at
any desired angle to the said parallel gauging faces, so that according as these faces
are moved to and from each other, the aforesaid line and scale cross each other at
points nearer to or farther from the zero of the scale, the distance of the point of
their intersection from the zero being proportional to the width between the
gauging faces of the bars. For example, if the scale or the line, which intersects it
be at an inclination of one in twenty, then in moving the gauging faces of the bars
a certain distance apart the point of intersection will have been moved twenty
times as far from the zero of the scale, thus magnifying the measurement twenty
times on the scale.
Instead of only one line being thus made to intersect the scale there may be
several such lines parallel to each other, the distance between them corresponding
to the total width iueasured by the scale, so that when one line intersects the scale
at its extremity the next line in order intersects it at its zero, each line being thus
made to serve for gauging a different denomination of thickness of the object
measured.

page_text: Fig. 1 of the accompanying Drawings shews a front view of one construction of
my before described measuring instrument; Fig. 2 shews a section on line X, X,
thereof. It consists, firstly, of a plate or bar A, having marked upon its face a
series of parallel lines marked 0, 1, 2, 3, &c., and having a projecting piece A¹, of
which a constitutes the one gauging face; secondly, a plate or bar B, B', of which
the part B is secured to a bar B2, and also to links C, C, by means of pins D, D, the
other ends of the links being pivotted to the back of the plate A, as shewn. Upon
the bar D is a projecting piece B³, the edge 6 of which constitutes the second
guaging face, which it will be seen is caused by the linked connection to move with
the parts B, B, in a direction to and from the gauging face a, parallel therewith.
The part B has an inclined edge at 61, on which is marked a scale as shewn, so
that as B is moved over the face of A from left to right, this inclined edge
intersects consecutively each of the lines 0, 1, 2, &c., at a constantly changing point
of its length, and any such point of intersection can be readily read off by means of
the scale. Thus in the position shewn in Fig. 1 the inclined edge b' intersects the
line 2 of A at the division marked "5" on the scale. The lines 0, 1, 2, 3, and the
divisions on the scale are so arranged relative to the gauging faces a, b, that when
these are brought close together by sliding B, B¹, over A, the scale will exactly
intersect the zero line of A at its zero division. The distances between the lines
0, 1, 2, 3, &c., and the divisions on the scale will depend upon the particular scale
or system of measurement which the instrument is desired to indicate; thus, if it is
desired to measure thicknesses in decimals of an inch, then the lines 0, 1, 2, 3, &c.,
are conveniently made one tenth of an inch apart, and if the extent of the scale is

page_text: limited between the two points where the edge b' intersects one line near the upper
end, and the next line near the lower end, as is the case in the Drawing, this
length may be conveniently divided into ten principal divisions, numbered to 10,
each of which will consequently represent a tenth part of one of the divisions
on A, that is to say, one hundredth part of an inch, and these divisions may be
again divided into any convenient number of subdivisions, such as 5, as on the
Drawing, each of which will consequently indicate th part of an inch.
From the above described arrangement it will be readily understood that if the
gauging faces a, b, have, in order to admit the object E to be gauged between them,
been moved apart such a distance that the scale of B intersects the line 2 of A at
the division "5," then the distance, and consequently the thickness, of the object
will be 25 inch, as the zero point of the scale will have moved away from the zero
line of A a distance equal to the two divisions to 1 and 1 to 2, plus one half the
division 2 to 3. It will be seen that the readings on the scale of fractional parts
of the distance between the lines 0, 1, 2, &c., will be magnified in the same
proportion as the total length of the scale is larger than the total distance between
the lines.
In order to adapt the instrument for taking inside as well as outside measure-
ments the projections A¹ and B3 may each be made a definite width relative to the
divisions on A; thus in Fig. 1 their width is assumed to be equal to 1 divisions
each, or both together=3 divisions, so that when a, b, are brought close together
the line o, which is then intersected by zero of the scale, will, in relation to the
outside edges of A¹ and B³ (which then constitute the gauging faces), represent a
measurement of 3 divisions, and thus by marking below the Figures 0, 1, 2, 3
respectively, the Figures 3, 4, 5, &c., the measurements for inside dimensions can
be read off therefrom. Although for facility of construction it is preferred to make
the piece B2 separate from the bar B, B¹, yet it will be evident that it may be in
one piece therewith; also in place of producing the parallel motion of the gauging
faces by the link attachment, as shewn, the bar B, B', may be so fitted to A as to
slide thereon in such manner as to maintain the accurate parallelism of the gauging
faces, but I prefer the link connection as the easiest means of effecting this. It
will also be evident that the motion of the bar B might be effected by means of a
micrometer screw connected to A, and that B may be secured in any position into
which it moved by means of a set screw. Instead of making the lines of A
parallel to the gauging faces and the scale of B inclined, the former might be
inclined at an angle to those faces, and the scale be parallel thereto, or both may
be inclined in opposite directions.
Fig. 3 shews a modified form in which the bars A and B, B¹, are connected by
links in a similar manner to a parallel ruler, the edges a, b, of these bars con-
stituting the gauging faces. The division lines 0, 1, 2, 3, &c., on A and the
inclined scale on B are arranged and operate in precisely the same manner as in
the first described arrangement.
Fig. 4 shews an arrangement in which the bar A has a cylindrical part A', on
which is marked a helical line, the convolutions of which are marked respectively
0, 1, 2, 3, &c., while the bar B, B1, has a hollow cylindrical part sliding over A¹,
and whose circular edge is marked with the scale as shewn. The bar A, up to the
point Z, is formed with a flat face, as shown by the cross section on line Y, Y, at
Fig. 5, against which slides the bar B; the gauging faces a and b are conveniently
formed on separate pieces fixed respectively to A and B, as shewn. In this
arrangement when the gauging faces are brought close together the zero division of
the scale on B' will intersect the convolution of the helical line on A. Instead
of forming a continuous helical line on A a series of parallel lines may be marked
thereon in a similar manner to the previous arrangements, such lines extending
either partly or wholly round the cylindrical surface. On the lines 0, 1, 2, 3, &c.,
on A may be circles parallel to the motion, in which case the edge of B carrying
the scale will be helical or oblique.

page_text: Having thus described the nature of my Invention, and in what manner the
same is to be performed, I claim,-
Constructing instruments for measuring small dimensions wherein two bars or
plates capable of parallel motion to or from or upon each other, and having
parallel gauging faces, are provided the one with a divisional line or divisional
lines, and the other with a scale crossing this or these at an angle, so that on
moving the one bar with its gauging face towards or away from the other gauging
face, the said line, or one of the said lines, and the scale intersect at a point nearer
to or farther from the zero of the scale, the distance between the gauging faces
being then directly read off at the said intersection, substantially as herein
described.
In witness whereof, I, the said John Milner, have hereunto set my hand and
seal, this Twenty fifth day of March, in the year of our Lord One thousand
eight hundred and eighty one.