Plate from 18th century encyclopedia showing illustrations of various mechanical principles and devices, and diagrams of mechanical forces. The main illustration shows a pile driver, a mechanical device used to drive piles into soil to provide foundation support for buildings or other structures. Also shown are different pulley, and block and tackle systems. A block and tackle is assembled so one block is attached to fixed mounting point and the other is attached to the moving load. The mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block. Various types of screw and worm drive systems are shown at the bottom.