log-ship

The Sailor's Word-Book

A small line about 100 fathoms long, fastened to the log-ship by means of two legs, one of which passes through a hole at the corner, and is knotted on the opposite side, while the other leg is attached by a pin fixed into another hole so as to draw out when stop is called, i.e. when the glass has run out. This line, from the distance of 10, 12, or 15 fathoms of the log-ship, has certain knots or divisions, which ought to be 47 feet 4 inches from each other, though it was the common practice at sea not to have them above 42 feet. The estimate of the ship's way or distance run is done by observing the length of the line unwound whilst the glass is running; for so many knots as run out in that time, so many miles the ship sails in an hour.


♦ To heave the log is to throw it into the water on the lee-side, well out of the wake, letting it run until it gets beyond the eddies, then a person holding the glass turns it up just as the first mark, or stray-line, goes out, from which the knots begin to be reckoned. The log is, however, at best, a precarious way of computing, and must be corrected by experience. The inventor of it is not known, and no mention is made of it till the year 1607, in an East India voyage, published by Purchas. The mode before, and even now in some colliers, and in native craft in the East Indies, is to throw a log or chip overboard at the foremost channel-plate, and to walk aft, keeping up with it until it passes the stern, thus estimating (and closely too by practice) the rate of motion. Other methods have been invented by various people, but Massey's Patent Log gives the most accurate measurement. The same principle is also applied to the deep-sea sounding-lead.

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