Year: 1893

page_text: Date of Application, 31st May, 1893-Accepted, 31st May, 1894

page_text: The frame slides with its guides n (Figure 4) along the bars 6 which are
parallel to the stirrup bar c. The distance P1, P2, Figure 7, or the distance of the
perpendiculars from PK and P¹ upon G which is a constant is represented in the
ellipsograph by the distance of the longitudinal centres of the two slots ¹ and ♬ª
which are set or rendered invariable or fixed when the ellipsograph is in use.
In one slot the pin moves correspondingly to PK (Figure 7) along an arc
of a circle and carries with it the two slots and which correspond to the
perpendiculars from PK and P¹ upon G (Figure 7). Now the sliding piece g¹
which describes the ellipse is fitted in so that it (9) can slide along the cross
piece and the said sliding piece g¹ is provided with the slott (parallel to
the elevated longitudinal stirrup bar c) in which the pin of the movable
sliding piece g works and the said movable sliding piece g¹¹ is operated by the
pin h.
The part 9' carries a vertically movable lead pencil-holder which is weighted
with a weight k (Figure 4). The said lead pencil holder can be raised clear of the
paper when required and be kept in the raised position by the engagement of a nose
or catch m in a disc u.
The abscissa produced by the sliding piece g¹ and the point of the lead pencil is
fully determined by the position of the pin (corresponding to the point Pк
Figure 7) and by the constantly preserved distance of the centres of the two
slots and from each other and this distance corresponds to the two perpen-
dicular lines from Pк and P' upon the line G (Figure 7).
Since the ellipse is formed from the oval by the movement of the several points
of the latter parallel to G (Figure 7) therefore analogously the sliding piece g¹ is
provided with a groovet parallel to c in which groove the pin / moves and the
said groove t retains its position parallel to c during the movement of the sliding
piece g along the slot ¹ of the piece q.
The use of the apparatus is shown in the following description :-If an ellipse
has to be drawn with the ellipsograph on a sheet of drawing paper, and if the same
be fixed for its size by the given axes, the ellipsograph must be adjusted according
to the desired axes. For this purpose, the screw d is first loosened and the arm f
is moved along the base of the spindle until the distance from the indicator o
which is shown (Figure 2) by a line on the projection upon the base of the spindle,
to the second indicator o2, which is shown as a line on the projection at the
extremity of the arm f, is equal to one half the major axis of the ellipse to be
drawn.
The screw d is then fixed, and here it is to be remarked that the indicators
marked o and o¹, which ought to be in the centres of the pins =, <¹, are removed
downward on the scale for the sake of convenience.
Any desired straight line is drawn on the sheet in question and
second one
parallel to the first and distant therefrom as far as the length of one half of the
minor axis. By means of the rider r, the crank handle e is fixed on the stirrup-
bar c whereby the arm f. is placed in a position at right angles to the stirrup bar.
The screws of the pieces 9 and g are then loosened and the apparatus placed in
such a manner on the upper of the two parallel lines above mentioned, at any
desired position thereof, that the indicators p, p¹ fall upon this line. Hereupon the
pieces and g¹ are moved on the frame, or on the rods, in such a manner that the
point of the pencil, changing at the same time its distance from the axis p, p, is
placed just above the abovementioned lower parallel line which lies at the
distance of half the minor axis from the axis p, p¹. It is very necessary that the
projection of the piece gl should not leave the groove t of the piece g¹. Sub-
sequently the screws of the pieces 9 and 9" are again fastened and then the
distance from the place where the pencil point is to the axis p p', is equal to half
the minor axis.
For the purpose of producing the ellipse exactly at the desired point, the major
and minor axes are in the first place drawn intersecting at this point, the whole
apparatus being then moved along the larger axis until the pencil point when

page_text: lowered falls upon the minor axis, (the markers p, p' always lying on the major
axis). If the rider be taken away, and the crank handle e be turned, the desired
ellipse will be produced according to the given major and minor axes in the desired
point on the drawing sheet.
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 :-
1. The ellipsograph substantially as set forth.
2. In an ellipsograph the combination of two devices which act together in such
a manner that the one draws the ellipse ou the surface of the drawing paper, whilst
it is at the same time influenced by a second device which corrects its movement
parallel to the surface of the drawing.
3. The specific form of ellipsograph illustrated in Figures 1 to 6 inclusive.
L 1
1000
J. G. LORRAIN,
Associate Agent.