Strap bound blocks, are single blocks, with a shoulder left on each side, at the upper part, to ad mit the strap through a little above the pin. These blocks are used at the clues of the square•sails for the clue-garnets, or clue-lines ; and under the yards, the shoulder preserves the strap from chafing.
Thick and thin, or quarter block, is a double block with one sheave, thicker than the other, and is used to lead down the topsail-sheets and clue-lines.
Although these are used for the topsail-sheets, and intended for the clue-lines, a single block would be cheaper and better, as the thin sheave is seldom used for the clue-lines, it being found rather to impede than to facilitate. Small ships in the merchant ser vice have a double block lashed in the middle of the yard as the quarter block, through which the sheets reeve, and lead down on opposite sides. Large ships in the merchant service have a single block lashed on each side of the middle of the yard, and the sheets reeve on their respective sides, and lead down by the mast.
Block voyal or viol, is a single sheaved block. The length is ten times the thickness of the sheave hole, which is three•eighths more than the thickness of the sheave ; • the thickness of the sheave is one-tenth more than the diameter of the viol; and the diameter of the sheave is seven times the thickness. The breadth of the block should be eight thickness of the sheave, and the thickness two-sevenths of the length. This block is double scored, the sheave is cocked with brass, and the pin is iron, and nearly as thick as the sheave. It is used in heaving up the anchor.
The viol passes round the jeer capstan, and through the block which is lashed to the main-mast, and the cable is fastened in a temporary manner to the viol in several places. It is seldom used except in the largest ships of the royal navy.
The_ blocks lashed to a ship's principal yards, are as follow : To the lower yards. The jeer block ; buntline blocks ; • leech line block ; //ft blocks and top-sail sheet blocks, strapped together ; quarter and slab line blocks, strapped together ; clue garnet blocks; tricimr blocks ; preventer brace blocks ; pendant blocks; studding•sail halyards blocks.
To the top-sail yards. Buntline and lye blocks, strapped together; top-gallant sheet block and tifi block, strapped together ; jewel block and brace pendant blocks ; • clue line blocks, and block to lead down the topgallant sheets.
To the top-gallant yards. Jewel, clue line, and brace pendant blocks.
To the mizen-yard. Jeer block ; derrick block ; signal halyard block ; throat broil, middle Grail, and soak broil blocks.
To the cross jack yard. Quarter blocks ; jeer blocks ; and lift and top-sail sheets blocks, strapped together.
To the bowsprit. The bee block, bolted to the bowsprit at the outer end under the bees ; fore bow line blocks, lashed on each side the fore stay collar; fore top-sail bowline block lashed to an eye bolt in the bowsprit cap.
Fish block, is hung in a notch at the end of the davit, and serves to haul up the flukes of the anchor to the sbip's bow.