Common, English or Hand log as used between 1574 till 1920( 60) The log and line was first described by William Bourne in 1574 and was used for measuring ship’s speed into the 20th century.
This wooden log-reel would originally have carried a line with knots tied at fixed intervals attached to a log-ship, a piece of board in the shape of the segment of a circle with its curved edge weighted. This was used to measure a ship’s speed. To do this, the log-ship was dropped overboard and the line was allowed to pay out from the log reel for a time set by a sand-glass. As the line paid out the number of knots that passed through the hand was counted, thus giving a measure of the ship’s speed. Knots in each 28 or 14 seconds on sand-glass