Improvements in Ellipsographs.
Year: 1895

page_text: Date of Application, 8th Jan., 1895-Accepted, 16.h Feb., 1895
Improvements in Ellipsographs.
I, JOHN HOTTINGER, of 506 Poplar Street, St. Louis, Mo., U.S.A., Gentleman,
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 relation to improvements in ellipsographs and consists in the
novel arrangement and combination of parts more fully set forth in the Specification
and pointed out in the drawing.
In the drawings,
Figure 1 is a plan view of the instrument after the marker arm has described a
quarter of a revolution;
Figure 2 is a middle vertical section of the same with the marker arm however in
its original position, that is, parallel to the supporting arms of the instrument;
Figure 3 is a bottom plan view of the washer-index; and
Figure 4 is a detail plan view of the adjustable arm to which the index and the
remaining parts are secured.
The object of my invention is to construct an ellipsograph which will be simple,
accurate, readily assembled, and one which shall be light and durable. To this end
I have devised an instrument which in detail can be described as follows:
Referring to the drawings, 1 is a frame of suitable design or outline having two
opposite turned-up edges 2, forming parallel grooves 3 within which is confined and
loosely adapted to revolve the generating circle 4. Extending from the center of
each of the edges 2 on the frame 1 is a slot 5 of suitable width the purpose of which
is hereinafter described. The normal position of the generating circle is that
indicated by the inner dotted circle in Figure 1, in which position the radial slot 6
thereof is superposed over the slot 5 of the frame (see also Figure 2). The slots 5
and 6 are of unequal width, the former being the wider to accommodate certain parts
as more fully to be described. Along one side of the slot 6 of the generating circle
is the eccentric scale 7 by which the eccentricities of the ellipse to be described are
determined. When the parts are in their normal position, the slots 5 and 6 are
respectively adapted to receive the enlarged circular head 8 of an arm 9, and its
upper rectangular reduced portion or offset 10. The circular head and offset 10
are thus shown simultaneously inserted into the slots 5 and 6 in Figure 2, the head
snugly fitting the slot 5 of the frame, and the offset 10 accurately fitting the slot 6
of the generating circle. From the offset 10 there extends a screw-threaded pro-
jection 11 over which is adapted to loosely pass a washer 12 of sufficient diameter
to overlap the meeting edges of the offset 10 and the slot 6. The washer has a
projecting pin 13 on its under surface adapted to pass into a suitable depression 14
on the surface of the offset, the object of this arrangement being to always keep the
washer in one position with respect to the remaining parts. A thumb nut 15 finally
secures and binds the arm 9 and the generating circle firmly together, allowing the
arm however to turn and slide within the slot 5 of the frame. The washer is pro-
vided with a notch whose short edge 16 serves as an index for the eccentric scale 7
on the circle.
The lower end of the right angular arm 9 carries a fork 17 within which is
lamped or secured by a thumb or binding screw 18 a movable tube 19. This tube
arries an extensible marker arm 20 clamped within the tube by a binding screw 21,

page_text: the free end of the marker arm carrying a clamp 22 within which is adapted to be
secured a pencil 23 or other suitable device. It is to be observed that the con-
nection between the center of rotation (that is the projection 11) and the tube 19
and its arm 20 need not be a right angular arm 9, for the said connection may be a
straight arm, but the former is preferable since when the tube 19 and arm 20
are pushed fully toward the arm 9, the pencil point comes directly under the center
of the projection 11, this marking the center of the ellipse. From the middle of
each side 2 of the frame projects outwardly the tubular extension 24 accommodating
the extensible bars 25 at the free end of each of which is the leg 26, each leg
carrying at the middle of the bottom' thereof a pointer 27 (see Fig. 2), the pointers
being in line with the continuation of the axis of the ellipse described by the
instrument, and hence serving to determine the direction of the major axis of the
ellipse to be described. Both the legs being outwardly extensible as well as
the marker arm, it is apparent that ellipses of variable lengths may be described
with this instrument.
It is apparent that if the arm 9 with its index is shifted to the zero mark on the
eccentric scale, and the parts then firmly set or secured, this being of course the
center of the generating circle, then if the circle be turned about its center within
its confines or grooves, 3, the pencil at the end of the marker arm will describe a
circle. If however the arm 9 with its index and other parts secured thereto is
shifted any number of points from zero along the eccentric scale, and the parts then
set as seen in Fig. 1, and the generating circle is turned, the marker arm will turn
with it, but instead of describing a circle, the center of rotation, being the center
of the screw-threaded projection 11 about which the arm rotates-will shift from
its original position along the slot 5 (as indicated by dotted and full lines in Fig. 1),
thus describing an ellipse, the minor axis thereof being equal to twice the distance
from the screw-threaded projection 11 fixed to the generating circle to the pencil
point (that is, the horizontal distance) and the major axis being equal to this
distance plus the distance that the center of rotation has shifted or travelled along
the slot 5 during one complete revolution of the generating circle, the amount
shifted being of course equal to twice the distance that the index was originally set
from the center or zero point along the scale. It is apparent too that the end of
the marker opposite to that which carries the pencil would describe an ellipse at
right angles to the main ellipse, the long axis of this second ellipse being twice
the distance from the center of rotation to that end of the arm, and the minor axis
being this distance minus twice the distance the index had originally been shifted
from the zero point along the eccentric scale.
It is of course within the spirit of my invention to reverse the general relation
between the frame and the generating circle, it being possible of course to have the
circle stationary and have the frame revolve instead.
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. An ellipsograph comprising a frame, grooves forming a part of the same, a
slot formed in said frame between the grooves, a generating circle mounted on said
frame adapted to revolve within the grooves, a radial slot carried by the circle, a
marker arm, means for securing the marker arm to the circle in any position along
the radial slot, and means for shifting the center of rotation of the marker arm
along the slot of the frame during the revolution of the generating circle, substan-
tially as set forth.
2. An ellipsograph comprising a frame, grooves forming part of the same, a
slot formed in said frame between the grooves, a generating circle mounted on
said frame and adapted to revolve within the grooves, a radial slot carried by
the circle, an eccentric scale adjacent to the radial slot, a marker arm carrying
an index co-operating with the scale, means for securing the marker arm to the
circle in any position along the scale, and means for shifting the center of

page_text: rotation of the marker arm along the slot of the frame during the revolution of
the generating circle, substantially as set forth.
3. In an ellipsograph, a suitable slotted frame, a generating circle mounted
on and adapted to revolve on said frame, a radial slot on said circle adapted
to be superposed over the slot of the frame, an arm having a rounded head
adapted to fit in the slot of the frame, an angular offset adapted to engage
with the slot on the circle, a screw-threaded projection extending from said
offset, a suitable index carried by the projection, means for securing the index
and the several parts together, and a scale on the circle co-operating with the
index, substantially as set forth.
4. In an ellipsograph, a suitable revolving arm, an offset carried by the
upper end of the same, a screw-threaded projection extending from the outer
surface of the offset, a suitable depression in said surface, a washer adapted to
pass over the projection, a peg on the under surface of the washer adapted to
enter the depression in the offset, a notch on said washer serving as an index,
and a thumb nut for securing the parts, substantially as set forth.
Dated this Sth day of January 1895
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.