After Ahab destroys his quadrant, he declares that “‘the level ship’s compass, and the level dead-reckoning, by log and by line; these shall conduct me, and show me my place on the sea. Aye,’ lighting from the boat to the deck, ‘thus I trample on thee, thou paltry thing that feebly pointest on high; thus I split and destroy thee!'”

“Level dead-reckoning, by log and by line” was an old method of determining a ship’s speed at sea. The term “log” is a misnomer, which Ishmael suggests by referring to the apparatus as “the wooden reel and angular log” attached hung.” The National Maritime Museum in Greenwich in the UK has a model of a log and line:


Here’s how the museum describes its use:

The log-reel, line, log-ship and sand-glass were used for determining a ship