Log

An instrument used for measuring the rate of a vessel's speed through the water. There are many kinds, the most ancient being known as the "old-fashioned chip log," and the patent logs (working by a series of cog wheels) are known respectively as the "Bliss American Taffrail Log," the "Walker Taffrail Log," the "Massey Harpoon Log," the "Cherub Log," and the spring log, known as the "Clark Russell Log." (See Current Log and Ground Log.)