Device for drawing ellipses

A device for drawing ellipses, comprising:

• a measuring stick having an upper face carrying graduated markings and a lower face restable on a flat surface on which the ellipse is to be drawn, the measuring stick being formed with a longitudinal slot extending the length thereof and closed at its ends, a cord having one end fixed to a first point on the measuring stick, a slide movable along the slot to align an indexing point thereof with a second point on the measuring stick, said slide including an upper section overlying the upper face of the measuring stick and a lower section underlying the lower face of the measuring stick, the two sections being connected to each other by a connection passing through said slot, said lower section of the slide being formed with a first bore aligned with said indexing point and extending transversely of the slide through which bore the cord passes, and with a second bore communicating with and at right angles to the first bore in the direction of the thickness of the slide, said upper section of the slide being formed with a pin passing through the slot of the measuring stick into said second bore and releasably engagable with the cord therein for fixing a predetermined length of the cord between the slide indexing point and the first point of the measuring stick, said first and second points of the measuring stick constituting the two focii of the ellipse to be drawn, and said predetermined length of cord being equal to the sum of the distances from said focii to all points on the ellipse to be drawn.