HOW IT WORKS.

equal surfaces, at right angles to those surfaces. The great natural philosopher Pascal first formulated this remarkable fact, of which a simple illustration is given in Fig. 179. Two cylinders, A and B, having a bore of one and two inches respectively, are connected by a pipe. Water is poured in, and pistons fitting the cylinders accurately and of equal weight are inserted. On piston B is placed a load of 10 lbs. To prevent