Improvements in the Joints of Mathematical Instruments for Measuring Angles and other purposes.
Year: 1893

page_text: Date of Application, 23rd Oct., 1893
Complete Specification Left, 25th June, 1894-Accepted, 23rd Oct., 1894
PROVISIONAL DEBULTIVATION.
Improvements in the Joints of Mathematical Instruments for
Measuring Angles and other purposes.
I, LIZZIE ANNA WALKER, of 27 Victoria Terrace, Kendall Lane, in the City
of Leeds, Governess, do hereby declare the nature of this invention to be as
follows:-
My invention has reference to certain improvements in mathematical instruments
for measuring angles.
And my said invention consists in a circular movement without a fixed centre of
the part or parts for reading or measuring off the angles.
According to my invention an upper part or plate moves on an under part or
plate (there may be two, three, or more plates) by means of a dovetail circular
slide or joint which may be formed either by separate plates or parts or by
cutting it in the solid. The said upper and under parts or plates may measure
respectively 20°, 30°, or any other degree. One plate may be constructed so as
to measure 5°, or 10°, or more degrees than the other, and this provision will
prevent the upper plate passing off the under one, this is only required in
instruments for measuring solids such as the T square, rule joint, and the like.
The degrees are marked upon the under or intermediate plate, the upper plate
passing round on it and indicating the angle.
In some instruments it will be necessary to provide means for preventing
separation of the parts and for this purpose flanges or projections and grooves, or
other such means, may be employed.
When it is desired to form a bevel, or to cause any instrument to remain
stationary at any given angle, the lower plate may be pierced at every 5° or 10°
and the upper plate provided with a hole through which a bolt or thumb screw can
be passed into the lower plate at the required degree.
To form an engineers' level the said plates measure 180° the lower plate is fixed
to a solid block the upper plate having attached to it a spirit level.
The military clinometer would require the lower or under plate to measure 200°,
and two upper plates of 90° each. A plomb line or spirit level would also be
required.
The parallel rule would require four joints, two corners giving from 90° to 180°,
and two from 0° to 90°. My said improvements are also applicable to station
pointers. Any of these instruments may have verniers attached to them to give a
more correct reading.
Dated this 20th day of October 1803
JOHN E. WALSH,
Royal Exchange Chambers, Boar Lane, Leeds,
Patent Agent to the Applicant'

page_text: .
Improvements in the Joints of Mathematical Instruments for
Measuring Angles and other purposes.
I, LIZZIE ANNA WALKER, of 27 Victoria Terrace, Kendall Lane, Leeds, in
the County of York, Governess, 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 has reference to certain improvements in mathematical instruments
for measuring angles.
It consists essentially in constructing the part or parts of the instrument for
reading off or measuring the angles which move one upon the other, with a circular
slide or joint whereby an accurate movement is obtained without a central pin
or pivot.
The invention will be fully described with reference to the accompanying
drawings in which its application to various forms of instruments or tools is
illustrated.
b
The
The instrument to which my invention is applied consists of two or more parts or
plates A and B one of which moves over and in proximity to the surface of the
other, with an angular movement about a centre situated at C or at a point outside
the instrument. According to my invention I obtain the accurate movement of the
parts A and B by means of a circular slide or joint D of dovetail or other
convenient form to hold the two parts together. The circular slide is formed by
two circular projections a on the part A and a single circular projection 6 on the
part B the projection 6 fitting into the recess between the two projections a.
projections a b on the plates A and B may be formed by cutting them out of the
solid or they may be formed or built up by riveting or otherwise attaching plates
of the required contour to the inner sides of the plates A and B respectively. In
this case construct them by riveting circular plates with inclined or bevelled
edges to the faces of the plates A and B so as to form a dovetail groove and a
dovetail projection 6 to fit therein. Instead of making the plates which form the
projections a and b with inclined or bevelled edges with the edge of the projection a
passing under the edge of the projection b. The plates A and B and the plates to
form the projections may be stamped out of sheet metal or may be made of any
other suitable material.
The plates A and B may be made of any desired size to measure from 20° or 30°
to any required number of degrees.
The degrees are marked on the projection a upon the under plate A the upper
plate B passing over it to indicate the angle.
Referring to Figs. 1 to 5 the invention is shown as applied to protractors the
instrument in Fig. 1 being applicable for measuring the external angles of solids
from 5° to 180° and the instrument in Fig. 2 for measuring internal angles from
90° to 175°. Internal angles may be measured from 50 to 170° by different
instruments. The remaining 5° (or more degrees) cannot be measured without the
plates being moved so that one would separate from the other. To prevent
separation the plate A is provided with a pin or lug a¹ and the plate B with a short
flange b' which prevent the two parts being moved sufficiently far round as to come
asunder. Fig. 3. shows an edge view or section of the plates A and B with a
dovetail groove formed in A and a dovetail projection b on B to form the circular
slide or joint, and Fig. 4. shows a similar view of the plates constructed with the
projection on one overlapping the projection on the other. Fig. 5. is a section
of Fig. 2.
Referring to Figs. 6, 7, and 8 the invention is shown applied to a square which

page_text: may be applied for measuring either internal or external angles. The plates A
and B with the circular slide or joint D upon which they move are attached to the
sides E of the instrument which may be of wood or other material or the
plates a and b may be attached direct to the sides E to form the circular slide D.
In the illustration the instrument is made with the surfaces of the two sides level
or in the same plane the material being cut away at the ends to the required depth
to receive the projecting plates a and b and allow the end of one side to fit over the
other. Fig. 6 shows the same open; Fig. 7. shows it closed, and Fig. 8 is a
longitudinal section. To allow the instrument to close as in Fig. 7 without the
parts separating either of the plates A and B may be made with 5° or more than
the other or 5° or more wider than the instrument is calculated to measure.
Referring to Fig. 9 the invention is shown applied to a T square.
Referring to Figs. 10 to 13 the invention.is shown applied to the joint of a rule.
The circular slide D is made in the way already described, the plates A and B
being so placed as to allow the sides F of the rule to open out into a straight line.
Fig. 10 shows the joint open, Fig. 11 shows it partially closed, Fig. 12 shows the
position of the plate A and projections a and Fig. 13 the position of the plate B
and projection b.
A square for joiners or mechanics use may be similarly made one of the sides F
being made with an additional piece applied at both sides to give it the desired
thickness, the other side forming the blade. To set the joint at or to indicate any
desired angle or bevel the plate B may be provided with a hole d and the plate A
with a series of holes 5° or more apart through which a pin or bolt may be passed
or one plate may have a projecting pin with a thumb screw passing through a slut
in the other by which the two can be clamped together stationary at any desired
angle. A similar arrangement of a pin on one plate working in a groove or slot in
the other may be adopted for preventing the two parts being separated.
Referring to Figs. 14 and 15 the invention is shown applied to the joints of a
pair of compasses, dividers, callipers or the like. The plate A has a circular slide
running 180° but only 90° become visible.
Referring to Figs. 16 and 17 the invention is shown applied to a military
clinometer the plate A measures 200° (or less) and is covered by two plates B
of 90° each. To the plates B are hinged two arms G which can fold up. A plumb
line H with a plummet his attached at the centre C of the plate A or instead of
the plumb line H a spirit level may be used. This instrument also serves as a
goniometer and protractor.
Referring to Fig. 18 the invention is shown applied to an engineer's level. The
plate A is riveted or otherwise attached to the block J the straight edge of A
being parallel with the side j. The plate B is connected thereto by the circular
slide D and carries or has attached to one side a spirit level K the instrument is
shown at an inclination of 20°.
Referring to Figs. 19 and 20 the invention is shown applied to a parallel ruler.
This instrument requires four joints the two long sides L L' have the plates A
attached to them and the two short sides or connecting links M M¹ carry the
plates B. Fig. 19 shows the instrument open and Fig. 20 shows it closed. When
open the indicator plate A on the side L is exposed and that on the side L' is
covered and the plate on L indicates from 90° to 0° and that on L' from 90° to 180°.
The two sides or links M M¹ indicate oblique angles to the two approaching
parallel sides L L'. The indicator on this instrument also serves as an indicator
for or to be used to indicate the distance apart of the two parallel sides L L'.
My said improvements are also applicable to station pointers and any other angle
measuring or indicating instruments.
Any of these instruments may have verniers attached to them to give a more
correct reading.
By this invention I am enabled to measure any solid external or internal angle
from the geometrical centre and indicate the degree on an under part or plate by
means of an upper part or plate passing over it.

page_text: Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. An instrument for measuring or indicating angles in which one part or plate
moves over another part or plate on which the indications are inscribed constructed
with a circular slide or joint connecting the two parts together whereby an accurate
movement of the parts is obtained substantially as described.
2. In an instrument for measuring or indicating angles the combination of the
plates or parts A and B and the circular projections a and b thereon forming a
circular slide of dovetail or other construction upon which the parts move relatively
to each other and by which an accurate angular movement is obtained substantially
as described.
Dated thin 10th do of Lune 1804