in nautical language, is a piece of wood usually in the form of a quadrant, with a radius of six inches. About a quarter of an inch in thickness, it is so loaded with a leaden plate, fastened to its circular side, that it swims in the water in a perpendicular position, with two-thirds under the surface.

LOG-LINE, The, used in navigation so early as 1570, and alluded to by Bourne in 1577, is a small cord with one end attached to the log, and the other to a revolving reel on board the ship. When the log is thrown overboard it keeps its place, as already described, while the log-line is unwound from the reel as the ship moves on, so that the length of line unwound in a given time indicates the rapidity of the ship's motion. The length of line given out is determined by pieces of coloured cloth called knots attached to it at distances of 50 feet, while the time is ascertained by a sand-glass of a given number of seconds, which bear nearly the same proportion to an hour that 50 feet bear to a mile. The number of knots, therefore, unwound from the reel in half a minute is the number of miles nearly which the ship runs in an hour. The log-line used by the royal navy is 48 feet in length.