Definition - What does Mechanical Log mean?
Mechanical Log is an instrument that is designed to calculate the distance covered by sailors. The log allows the sailors to get the more accurate estimates of the distance traveled by them at any given time. It also lets them know the speed of the ship and estimate the time it would take to reach their destination. The distance traveled at sea is measured in the nautical miles which are equivalent to 1.852 kilometers or 1.15 miles.
Petropedia explains Mechanical Log
Edward Massey successfully invented the first Mechanical Log in 1802. He was an instrument maker. The force of water makes the rotator to turn when the instrument is thrown into the sea. The rotator draws and spins in the water as the ship moves along. Dials which are connected by a mechanism with the rotator show the speed of the ship. It is necessary to keep a record of the readings of the speed of the ship to estimate the position. Due to the shape of these logs, they are also called harpoon ship logs.