A New or Improved Device for Measuring and Setting out Angles.
Year: 1897

page_text: I, EDWARD HARNETT, of "Rothsay," 104, Melody Road, New Wandsworth,
Gentleman, do hereby declare the nature of this invention to be as follows:-
:-
My invention relates to a new or improved device for setting out and measuring
angles and which is a combination of a mathematical instrument and a working
tool, practically employing and combining the line of chords with a jointed rule,
sector, or angle measurer.
For use in connection with mathematical drawings it may be usefully employed
for measuring any given angle and to ascertain the number of degrees contained
therein, while it may also be employed for protracting angles of any given size.
As a tool for practical mechanics it is most simple and efficient for measuring
and setting out angles, it possesses a greater range of adaptability than any other
tool and is very accurate in its work.
In carrying my invention into practical effect, the instrument comprises
essentially two arms or legs of equal length which represent two radii of a circle
moveable about the centre of a joint, which joint represents the centre of the circle.
The joint is preferably made by means of a projecting screw threaded pin, brazed
or suitably secured to the end of the lower arm or leg and passing through a corre-
sponding hole or perforation, in the upper arm or leg, the two arms or legs being
locked or secured together in any required position to represent any angle by means
of a screw knob, thumb nut, or the like.
The top arm or leg is marked with the simple line of chords such as at present
used for setting off or measuring angles, while the lower arm or leg is marked with
a line having but a single point or indent which is designed to receive the leg of
the compass, or the like used in measuring the number of degrees in the angle.
Dated this 2nd day of September 1897.
A New or Improved Device for Measuring and Setting out Angles.
I, EDWARD HARNETT, of "Rothsay," 104, Melody Road, New Wandsworth,
London, Gentleman, do hereby declare the nature of this invention and in what
Price 8d.]

page_text: manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
My invention relates to and consists of a new or improved device or instrument
for measuring and setting out angles, whereby, what is known to mathematicians
as the line of chords" is combined with the two legs or members of a rule or
bevel in such a manner as to constitute a sector of greater practical utility than
that which has hitherto been obtained, and which will be readily understood and
applied in practice by mechanics, artisans and others.
In order that my invention may be fully understood I will now proceed to
describe same with reference to the accompanying drawings in which Fig. 1 is
a plan of the device with the legs extended, Fig. 2 a side elevation with the legs
closed, and Fig. 3 an underside plan, also with the legs closed.
a and b are the two legs or members jointed together as shown, preferably by
means of a screw pin p (Figs. 2 & 3) brazed or suitably secured to one of the legs
or members a, and passing through a hole or perforation formed in the second
leg or member b, the two being clamped together in the required position by a
thumb-nut or the like such as n.
I as
I do not restrict myself to this particular method of joining the legs or members a
and 6 together, as a rivet such as c may be employed for this purpose, which would
be sufficiently tight to prevent the legs shifting or moving from any position in
which they had been set, but at the same time allowing of their being moved accord-
ing to requirements.
The centre of the joint e is provided or marked with the point d and from this
latter radiate the straight lines d e and d f central with and parallel to the edges
of the said legs or members a b. On the straight line de I engrave or mark in any
convenient manner the scale of chords as shown, and on this line and at a distance
from the centre point d of 60 degrees on the said line of chords I provide the centre
point g, while I also provide a similar point on the radial line d f equi-distant
from the said centre point d. The points g and h are distant from the point d an
amount (60 degrees) equal to the radius to which the line of chords is laid down.
To measure the angle of any object, the legs or members a and b are set to fit
the object of which it is desired to measure or ascertain the angle; the leg of an
ordinary compass or dividers is then placed in the centre of the point h and the
other leg of the compass or dividers extended to the centre point g. With the
compass or dividers thus extended one of its legs is placed in the centre point or
zero d and the other leg of the compass or dividers will then extent along the line
of chords de to the number thereon indicating the degrees contained within the
angle thus measured.
In order to set the instrument to any desired angle, it is only necessary to pro-
ceed as follows:-
Place one leg of the compass or dividers in the centre point or zero d and extend
the other leg along the line de of the scale of chords to the number of degrees
thereon indicating the angle required, then with the compass, dividers or the like
thus extended, place one of its legs in the centre point on the line d f and adjust
the legs a b of the instrument or sector so that the other leg of the compass,
dividers or the like will meet the centre point g on the line of chords de, and the
instrument or sector will then be set to the required angle.
If the angle to be measured or set out be greater than 90 degrees, it can be ascer-
tained by setting one leg or member of the instrument against a straight edge
and while holding the other leg firmly the free leg is then set back to the straight
edge, the smaller angle thus obtained when deducted from 180 degrees gives the
required angle, or the latter may be ascertained by measuring the supplement of
the angle and deducting the number of degrees in the angle so ascertained from
180 degrees, which gives the number of degrees in the greater angle required.
Any desired scale or scales such as inches for instance may be engraved or other-5
wise suitably marked on the backs or edges of the legs or members a b of the said

page_text: instrument or sector in addition to the line of chords, the radial lines d e and d f.
and the centre points d, g and h.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is-
1/. The new or improved instrument device for measuring and setting out angles,
substantially as herein described and shown with reference to the accompanying
drawings.
2. The new or improved instrument or device for measuring and setting out
angles consisting of two straight parallel legs ab suitably pivoted together as at c,
in combination with the radial lines d e and d f running central to and parallel
with the parallel edges of the legs a b, and meeting or intersecting at the centre
point d; the centre points g and h; and the scale of chords; the whole combined
and arranged for the purposes specified, substantially as herein described and shown
with reference to the accompanying drawings.
·ושת
تيمم
1
1000
F. G. CASSELL
(Of Cassell & Co.),
22, Glasshouse Street, Regent Street, London, W.,
Agent for the Applicant.