Page:Life in Motion.djvu/70

 recording the velocity of the wind, which registered its movements on a sheet of paper rolled round a cylinder moved by clockwork. Magellan, in 1779, made designs for an instrument for recording automatically many meteorological phenomena. In 1794, Rutherford constructed a thermometer by which curves of changing temperatures were marked on blackened paper. Thomas Young, one of the founders of this Institution, in 1800, showed how time could be measured on the surface of a cylinder moving at a uniform speed. The celebrated James Watt devised a method of tracing the movements of the indicator of his engine on a cylinder rotated by the engine itself. Thus he obtained a curve showing variations of steam-pressure at different times. During the past thirty years, numerous ingenious instruments have been invented by physiologists for recording movements; but no physiologist has done so much in this direction as Professor Marey of the College du France, to whom we are largely indebted for the development of the graphic method to its present condition of precision and convenience.