BLOCK, in the rigging of a ship, is an important part of the apparatus necessary for raising sails and yards, tightening ropes, etc. The B. comprises both the frame or shell, and the pulley or pulleys contained within it. In seamen's language, a tackle includes the rope as well as the B. through Which it works. The uSes of blocks are very numerous on shipboard; and to subserve these uses, they arc distributed about the masts, yards, sails, and ropes. They vary greatly in size, shape, power, and designation; but nearly every B. comprises a shell or wooden exterior, a shease or wheel on which the rope runs, a pin or intle on which the sheave turns, find a strap (of rope or iron) to fasten the B. to any particular station (see PULLEY). A single B. contains only one sheave; a double B., two; and so on. Besides the designations of blocks according to the number of sheaves they contain (single, double, treble', fourfold), ships' blocks receive numerous other as B., B., etc. Some of these names depend on the kind of service, others on the place of fixing; while the rest are examples of the odd nomenclature adopted by seamen.
Bloek-azaking.—Ships' blocks were made by hand until about a century ago. But mere workers in wood could not produce them; it required unusual skill and practice to fashion the several pieces, and put them together so as to possess the requisite strength and facility in working. The trade was either carried on alone, or in conjunction with mast-making. More than 1400 such blocks were required for one of the old 74's, and a proportionate number of vessels for larger or smaller size. In 1781, a Mr. Taylor began to make the sheaves and shells of blocks by a process which he had invented. Ile made
all the blocks for the royal navy until the expiration of his patent rights. The admiralty then commenced the manufacture on their own account. In 1801, Mr. (afterwards Sir) Mark Isambard Brunel submitted to the admiralty a working-model of a very beautiful system of machinery for block-making; it was accepted, and the inventor engaged to set up the apparatus at Portsmouth. So intricate was the machinery, and so great the difficulty in procuring the several working-parts from the machinists of those days, that it was not until the year 1808 that the system was put into effective operation. It was then, however, so perfect that very few additions or improvements have since been needed. The machinery made blocks more accurately than they had ever been made by hand, and with the aid of ordinary workmen only. It could effect 4:50,000 worth of work in a year, or 140,000 blocks, by the assistance of 10 men attending the machine. Duplicate machinery was made for Chatham. Brunel received :I.-:20,000 for his invention and for his personal superintendence until the machinery was brought into working order; this sum was money well laid out, for the machine saved to the country nnA than £20,000 a year, in the busy warlike period from 1808 to 1815. The machinery it-self is too complicated to be described except at a length incompatible with the limits of this work; but it may be stated in a general way, that the system is made up chiefly of saws and lathes, combined with great ingenuity. The blocks are made of elm, and the sheaves of lignum vita;; the pins are of iron, carefully prapared to avoid friction as much as possible.