606 



BLOCK. 



Uloclc. 



Plate 

 LVIII. 

 Fig. 2. 



Plate 

 LVIII. 

 Fig. 3. 



bit ween the block and the yard ; they are also used 

 at thi outer end of the boomkins, to lead in thefore- 

 .. Sec Plate LVIII. Fig. 2. 



r blocks, are similar to two single blocks, and 

 are formed out of a solid piece, about 20 inches long, 

 one above the other. Between the blocks is a scoring 

 for a middle seizing : A round head is turned at each 

 end, and hollowed underneath to contain the end 

 seizings; along the sides, through which the pins are 

 driven, is a groove or scoring, large enough to re- 

 ceive part of the topmast shrouds, in which it is 

 seized. These blocks receive the lifts and reef tackle 

 pendents of the topsail yards. 



Spring block, a new kind of block, invented by 

 Francis Hopkinson, Esq. of Philadelphia, and de- 

 signed to assist a vessel in sailing, by increasing the 

 acting spring of her rigging. It is proposed to :ippiy 

 it to all such parts of the rigging as will admit of it 

 with safety and convenience, and where its operation 

 will be most advantageous, but particularly to the sheet 

 ropes, and, if practicable, to the dead eyes, in lieu of 

 what are called the chains. A, (Plate LVIII. Fig. 3.) 

 is a block made in the usual manner, having a ring or 

 eye B at one end ; c is a spiral spring linked at one 

 end to the hook DE, and at the other to the ring F, 

 which is to be annexed to an eye-bolt at the timber- 

 head, or by some other means, to the place where it 

 is to be applied. The spring c must be of well tem- 

 pered steel, and proportioned in strength to the ser- 

 vice it is to perform. When used, two of these 

 blocks are employed, one attached to the timber- 

 heads and the other to the sail. Within the cavity 

 or pipe, formed by the spiral spring, there must be 

 a chain of suitable strength, called a check chain, 

 (represented in the centre of the spring,) connected 

 by the links to the hook DE and ring F. When 

 the spring is not in action, this chain is 6lack ; but 

 when the spiral spring is extended by the force of 

 the wind, as far as it can be without danger of in- 

 jury, the check chain must then begin to bear to 

 prevent its further extension, and if strong enough, 

 will be an effectual security against failure. The in- 

 ventor of this machine apprehends, on good grounds, 

 that a vessel thus furnished will be less liable to heel ; 

 and that she will receive the impulses of the wind to 

 better advantage, and sail with a more lively and 

 equable motion, than if rigged in the common way. 

 We have never heard of its being tried ; but fear the 

 weight of a spring sufficiently strong to have any 

 effect on a large sail, would be very unmanageable, 

 particularly aloft, from its weight, and would also be 

 very expensive. There is no doubt if this, or a similar 

 contrivance, could be applied to a sail, it would have a 

 good effect : for instance, when a ship is sailing with 

 a certain rate, if a suuden blast of wind comes, but does 

 not continue, it will not advance the vessel at all ; be- 

 cause it does not continue long enough to communi- 

 cate an increased momentum to so large a mass as a 

 ship, though, at the same time, it may make her heel 

 or pitch violently. If her rigging is fitted with these 

 springs, she would receive the impulse of the same 

 blast in a regular and progressive manner, which 

 would tend to increase her velocity instead of causing 

 her to heel. We think it would be very improper 

 and dangerous to apply any thing of this kind to the 



shrouds. We recollect meeting with a similar inten- 

 tion, to be effected by a cylinder, fitted with a pis- 

 ton, which, when drawn out, would cause a vacuum, 

 and act as a strong spring. By this means a sufficient 

 clastic force might easily be obtained ; but it would 

 be difficult, nay, impracticable, to preserve such a 

 cylinder in an acting state at sea, unless it were situa- 

 ted beneath the deck, and defended from the weather, 

 &c, and then it could not be applied to the upper kails. 

 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 cluc-hnes ; and under the yards, 

 the shoulder preserves the strap from dialing. 



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 thicknqss. The breadth of 

 the block should be eight times the thickness of the 

 sheave, and the thickness two-sevenths of the length. 

 This block is double scored, the sheave is coaked 

 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 lashtd 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 ; buntlinc 

 blocks ; leech line block ; lift blocks and top-sail 

 sheet blocks, strapped together ; quarter and slab- 

 line blocks, strapped together ; clue garnet blocks ; 

 tricing blocks ; preventer brace blocks ; pendant 

 blocks; studding-sail halyards blocks. 



To the top-sail yards. Buntlinc and tye blocks, 

 strapped together; top-gallant sheet block and lift 

 block, strapped together ; jewel block and brace- 

 pendant blocks ; clue line blocks, and block to lead 

 down the top-ga!lanl sheets. 



To the top-gallant yards. Jewel, clue line, and 

 brace pendant blocks. 



To the mixen-yard. Jeer block ; derrick block ; 

 signal halyard block ; throat brail, middle brad, and 

 coak brail blocks. 



To the cross-jack yard. Quarter blocks ; jeer 



Biock. 



