‹‹‹ Vitr. 10.2.9 | Table of Contents | Vitr. 10.2.11 ›››
10This species of machine is called Polyspaston, because the facility and dispatch in working it, is obtained by means of many pulleys. One convenience in using a single pole is, that the situation of the weight in relation to the pole, whether before it or to the right or left of it, is of no consequence. All the machines above described, are not only adapted to the purposes mentioned, but are also useful in loading and unloading ships, some upright, others horizontal, with a rotatory motion. On the ground, however, without the aid of the poles, ships are drawn on shore by the mere application of blocks and ropes.
10This kind of machine is called a polyspast, because of the many revolving sheaves to which its dexterity and despatch are due. There is also this advantage in the erection of only a single timber, that by previously inclining it to the right or left as much as one wishes, the load can be set down at one side.
All these kinds of machinery described above are, in their principles, suited not only to the purposes mentioned, but also to the loading and unloading of ships, some kinds being set upright, and others placed horizontally on revolving platforms. On the same principle, ships can be hauled ashore by means of arrangements of ropes and blocks used on the ground, without setting up timbers.