HEART WHEEL

The name given to a well-known mechanical contrivance for converting a circular motion into an alternating rectilinear one, common in cotton mills. It is an ellipse turned either on an axle, or by means of a winch and handle on one of its foci, or its centre, on whose edge a moveable point or circle pre es: the latter receives an alternating motion from the circumference of the ellipse, which in its revolution pre es it to different distances from the centre of motion. The practical disadvantages of this connivance are the inequality of pre ure and of moving force which will be required at different parts of the rotation of the ellipse, and the consequent wearing of some parts of it faster than others. (Gregory's Mechanics, vol. ii.) [s. 562]