Taut Wire Measuring Gear. Used in surveying ships to indicate an exact distance run. About 140 miles of pianoforte wire is carried on a drum, one turn being led round a 'counter' wheel having a circumference of .01 of a cable, 0.001 of a mile. End of wire is weighted and lowered to sea-bed. As ship goes ahead, the wire is allowed to go out. Number of revolutions of 'counter' wheel is registered, thus giving a distance. Accuracy is within 0-2 per cent.
Tavistock Theodolite. Instrument used for precise measurement of angles in marine surveys.