POINSOT, Louis

A remarkable work». (DSB). L. Poinsot (1777/1859), a graduate of the Polytechnic School in Paris, and for many years member of the superior council of public instruction, published in 1804 his Elements de statique. This work is remarkable not only as being the earliest introduction to synthetic mechanics, but also as containing for the first time the idea of couples, which was applied by Poinsot in a publication of 1834 to the theory of rotation.A clear conception of the nature of rotary motion was conveyed by Poinsot's elegant geometrical representation by means of means of an ellipsoid rolling on a certain fixed plane. This construction was extended by J.J. Sylvester so as to measure the rate of rotation of the ellipsoid on the plane» (Cajori, p. 455)