JACK-STAYS. Ropes, battens, or iron bars placed on a yard or spar and set taut, either for bending the head of a sail to, or acting as a traveller. Frequently resorted to for the staysails, square-sail yard, &c.
JACOB'S LADDER. The assemblage of shakes and short fractures, rising one above another, in a defective single-tree spar. Also, short ladders made with wooden steps and rope sides for ascending the rigging.
JACOB'S STAFF, or Cross-staff. A mathematical instrument to take altitudes, consisting of a brass circle, divided into four equal parts by two lines cutting each other in the centre; at each extremity of either line is fixed a sight perpendicularly over the lines, with holes below each slit for the better discovery of distant objects. The cross is mounted on a staff or stand for use. Sometimes, instead of four sights, there are eight.
JACULATOR. A fish whose chief sustenance is flies, which it secures by shooting a drop of water at them from its mouth.
JAG, To. To notch an edge irregularly.—Jagged, a term applied to denticulated edges, as in jagged bolts to prevent their coming out.
JAGARA, or Joggaree. A coarse brown sugar of India.
JAGS. Splinters to a shot-hole.
JAIL-BIRD. One who has been confined in prison, from the old term of cage for a prison; a felon absurdly (and injuriously to the country) sentenced to serve in the navy.
JALIAS. Small craft on the Arracan and Pegu coasts.
JAM, To. Anything being confined, so that it cannot be freed without trouble and force; the term is also applied to the act of confining it. To squeeze, to wedge, to press against. (See [Jambing].)