Emerson, William, The principles of mechanics : explaining and demonstrating the general laws of motion ; the laws of gravity, motion of descending bodies, projectiles, mechanic powers, pendulums, centers of gravity, &c., strength and stress of timber, hydrostatics, and construction of machines ; a work very necessary to be known by all gentlemen and others that desire to have an insight into the works of nature and art, and extremely useful to all sorts of artificers, particularly to architects, engineers, shipwrights, millwrights, watchmakers, &c., or any that work in a mechanical way