An Universal Dictionary of the Marine / Or, a Copious Explanation of the Technical Terms and Phrases Employed in the Construction, Equipment, Furniture, Machinery, Movements, and Military Operations of a Ship. Illustrated With Variety of Original Designs of Shipping, in Different Situations; Together With Separate Views of Their Masts, Sails, Yards, and Rigging. to Which Is Annexed, a Translation of the French Sea-terms and Phrases, Collected from the Works of Mess. Du Hamel, Aubin, Saverien, &c.

by William Falconer

A cask, box, &c. is also said to be jammed, when it is in the same manner wedged in between weighty bodies, so as not to be dislodged without great difficulty.

JEARS, or GEERS, drisse, an assemblage of tackles, by which the lower yards of a ship are hoisted up along the mast to their usual station, or lowered from thence as occasion requires; the former of which operations is called swaying, and the latter, striking. See those articles.

In a ship of war, the jears are usually composed of two strong tackles, each of which has two blocks, viz. one fastened to the lower-mast-head, and the other to the middle of the yard. The two blocks which are lashed to the middle, or slings of the yard, are retained in this situation by means of two cleats, nailed on each side, whose arms enclose the ropes by which the blocks are fastened to the yard. The two ropes, which communicate with these tackles, lead down to the deck on the opposite side of the mast, according to the situation of the upper jear-blocks.

The jears, in merchant-ships, have usually two large single blocks on the opposite side of the mast-head, and another of the same size in the middle of the yard. The rope, which communicates with these, passes through one of the blocks hanging at the mast-head, then through the block on the yard, and afterwards through the other hanging-block upon the mast. To the two lower ends of this rope, on the opposite sides of the mast, are fixed two tackles, each of which is formed of two double blocks, the lower one being hooked to a ring-bolt in the deck, and the upper one spliced, or seized into the lower end of the great rope above, which is called the tye. By this contrivance the mechanical power of the tackle below is transmitted to the tye, which, communicating with blocks on the yard, readily sways up, or lowers it, either by the effort of both jears at once, on the opposite sides of the mast, or by each of them separately, one after the other.

JETTY-HEAD, a name usually given, in the royal dock-yards, to that part of a wharf which projects beyond the rest; but more particularly the front of a wharf, whose side forms one of the cheeks of a dry or wet dock.

JEWEL-BLOCKS, a name given to two small blocks, which are suspended at the extremity of the main and fore-top-sail-yards, by means of an eye-bolt, driven from without into the middle of the yard-arm, parallel to its axis. The use of these blocks is to retain the upper-part of the topmast studding-sails beyond the skirts of the top-sails, so that each of those sails may have its full force of action, which would be diminished by the incroachment of the other over its surface. The haliards, by which those studding-sails are hoisted, are accordingly passed through the jewel-blocks; whence, communicating with a block on the top-mast-head, they lead downwards to the top or decks, where they may be conveniently hoisted. See the article Sail.

JIB, foc, the foremost sail of a ship, being a large stay-sail extended from the outer end of the bowsprit, prolonged by the jib-boom, towards the fore-top-mast-head. See Sail.

The jib is a sail of great command with any side-wind, but especially when the ship is close-hauled, or has the wind upon her beam; and its effort in casting the ship, or turning her head to leeward, is very powerful, and of great utility, particularly when the ship is working through a narrow channel. See Sailing.

Jib-Boom, a boom run out from the extremity of the bowsprit, parallel to its length, and serving to extend the bottom of the jib, and the stay of the fore-top-gallant-mast. This boom, which is nothing more than a continuation of the bowsprit forward, to which it may be considered as a top-mast, is usually attached to the bowsprit by means of two large boom-irons, (see the article Iron-Work) or by one boom-iron, and a cap on the outer-end of the bowsprit; or, finally, by the cap without, and a strong lashing within, instead of a boom-iron; which is generally the method of securing it in small merchant-ships. It may therefore be drawn in upon the bowsprit, as occasion requires, which is usually practised when the ship enters a harbour, where it might very soon be broke, or carried away, by the vessels which are moored therein, or passing by under sail.

JIBING. See Gybing.