GB141400A - Improvements in ellipsographs - Google Patents

Abstract

141,400. Last, J. Dec. 10, 1918. Ellipsographs.-An ellipsograph comprises a Hooke's joint A constrained to move in a circle inclined to the plane of the ellipse to be drawn, and carrying a pen, pencil, &c. h maintained perpendicular to the plane of the ellipse. The instrument is constructed with three legs e<2>, e<3>, e<4>, the legs e<2>, e<3> carrying a semicircular slotted archpart E on which is adjustably mounted a rotatable spindle C secured by a screw d<2> and nut d'. A plate B is secured to the spindle C and carries a screwed rod b<2> on which is mounted a slide b<1> carrying one axis of the joint A. A stem f<1> depends from the joint A and slides within a member f<11> carrying the pen h, a pin f<2> on it engaging a slot f<3> in the member f<11>. Links j, k extend between the member f<11> and the leg e<2> so as to keep the member f<11> vertical during its movements, and a weight m presses the pen on to the paper against the action of a spring l. When the instrument is to be used, the points of the legs c<2>, e<3> are placed on the minor axis and the point of the leg e<4> on the major axis. The spindle C is then turned so that the axis of the rod b<2> is horizontal, and the rod is rotated until the pen is at one end of the major axis. The spindle is then turned so that the pen is on the minor axis, and the position of the spindle C with relation to the slot in the arch E is adjusted so that the pen is at one end of the minor axis. The spindle C is then rotated to cause the pen to describe the ellipse.