An Improved Micrometer Gauge.
Year: 1888

page_text: Date of Application, 18th Dec., 1888
Complete Specification Left, 14th Sept., 1889-Accepted, 9th Nov., 1889
PROVISIONAL SPECIFICATION.
An Improved Micrometer Gauge.
EDWARD BRIDGWATER LANCASTER, 367 Cooksey Road, Small Heath, Birmingham,
Tool Maker do bereby declare the nature of this invention to be as follows:-
Invention consists of two long bars, A, A, each swinging on an axis F. fixed in
foundation plate. Also two equal bars, B, C, at short and equal distances on opposite
sides of the line joining the fixed axes, and parallel to that line, are jointed to
bars, A, A, freely; thus ensuring perfect parallelism, in all positions of the swinging
bars, of the surfaces between which the solid is placed (i.e., the ends of bars, B, C,
and faces of blocks opposite to them).
Another bar, D, also parallel to line joining fixed axes, jointed similarly, at M times
the distance of B from that line, carries vernier, with similar motion along index,
therefore traversing M times space through which B moves, thus magnifying
dimension of solid M times and making possible the graduation of index by lines
parallel to faces of blocks.
Dated this 15th day of December 1000.
COMPLETE SPECIFICATION.
An Improved Micrometer Gauge.
I, EDWARD BRIDGWATER LANCASTER, of 367 Cooksey Road, Small Heath,
Birmingham in the County of Warwick Tool maker 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 statement :--
My invention relates to an improved micrometer gauge, and has for its objects the
attainment of perfect accuracy in the measurement of solids, and also the measure-
ment of angles.
In order that my invention may be the better understood, I have appended the
accompanying sheet of drawings, shewing a plan view of the device or contrivance
according to my invention, the figure being drawn to scale.
Upon a suitable foundation or base plate I arrange two bars, A A², pivotted at B B¹
to a block C which is firmly attached to said base plate, or said bars A A' may be
mounted upon pins at B B¹ so as to move freely thereupon, and said pins may be
screwed into, or otherwise attached to the base plate. A cross bar E, with two true
faces FF is jointed to the bars A A¹ at D, D' and exactly in a line with said
faces F F I fix two blocks, or fixed faces J Ji, to the base plate. A second cross
bar H is jointed at G G₁ to the parallel bars A A¹, so that the faces [ I' thereof may
be opposite to, and correspond with two fixed faces or blocks K, K₁ similar to the
blocks J J. A third cross bar. L jointed to the ends of the bars A A¹ at M M¹
carries a vernier N suitably divided into fractional parts of the scale O, which is
attached to the foundation plate P. This scale O is sufficiently wide to allow of the
division of its degrees by the vernier N at any part of the range of the instrument,
and said vernier in common with the cross bars E and H has a parallel movement.
C
The moveable faces F F¹ and I I' also, during the movement of the bars A A¹
upon the fixed pivots B B₁ maintain perfect parallelism relatively to the fixed faces
or blocks J J and K K¹. The latter may be socketed as shown, so as to allow of
adjustment or removal when necessary, and these may also be fixed upon the base or
foundation plate at various distances from the normal, or zero positions of the
faces F F and I I¹ so as to admit there between solids of different dimensions for
measurement.

page_text: In using the improved micrometer gauge according to my said invention for
accurately measuring the dimension of any solid interposed between the moveable
faces F F and I I³ and the fixed faces J J and K K¹, any difference in said
dimension is magnified by the movement of the vernier N upon the scale O, thus,
the distance between the centres M and B being n times greater than the distance
between B and D, any variation of the position of the moveable face F and the
fixed face J will be magnified n times by the movement of the vernier N, corre-
sponding to the dimension between F and J.
==
In order to make use of the instrument for the gauging or measuring of angles,
I attach to one of the bars A or A', a plate P, the two edges of which represent an
angle of 90°, and said plate P is attached to A' in such a manner that the edges a¹
and a are at such angles with the edges and 6 of the bar H, that the sum of the
two angles shall equal 90° at any position of the vernier N upon the scale O.
Therefore, when the parallel bars A 'A' are perfectly vertical the angle between a
and b = 30° and the angle of a¹ and 6¹ 60°, and the first line of the vernier N is
opposite to the figure 5 upon the scale O. Referring to the table of natural sines
upon the drawing it will be seen that sin 30° = 5000, therefore I use the line
marked 5 upon the scale as a datum line, or starting point, and measurements are
read off from right or left of said line, as the angle may exceed 30° or 60°. As an
example, if it be required to measure a solid with angular surfaces, the unknown
angle being 47°, and the surfaces placed against b and a, it will be found that the
reading of the vernier upon the scale O will be 2.9237, and, as the radius B M = 10,
reference to the table. of sines shews that sin 17° = 29237, therefore 17° + 30°
the angle required, and represented by the surfaces of the solid. If, however, said
surfaces had been interposed between a¹ and 6¹ the reading of the vernier upon
scale would have also been 2.9237 = sin 17°, but in this case the subsequent
estimation of the required angle would have been
=
47°
When the vernier is at zero, a¹ 6₁ = 90° and a b=0°, the zero of course being
to the right of the datum line 5.
It is evident that the table of sines need not extend beyond sin 30°, for the
measurement of angles between 0° and 90°.
Although I have shewn a scale upon the drawing to indicate the proportions of the
instrument, I do not confine myself to the size shewn nor to the manner and style
of dividing the vernier N and scale O which may be set out in terms involving any
dimensions or attributes of the solids to be measured.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is;
First. The improved micrometer gauge substantially as herein described and shewn
in the accompanying drawing.
Second. In a micrometer gauge, the employment of parallel bars A A¹, cross
bars E H, and vernier N in combination with a scale O and fixed faces J K and J¹ K'
substantially as and for the purposes herein set forth with reference to the drawing.
Third. In a micrometer gauge the employment of a plate P in combination with
the appliances mentioned in the preceding claim, for the measurement of angular
bodies by computation from the sines of said angles; substantially as herein described
and shewn in the drawing appended hereto.
Dated this 16th day of September 1889.
FREDK. WALKER & HYDE,
4, Little Moorfields, London, E.C., Agents for the Applicant.