A2 Harpoon ship's log

Maker Thomas Walker

Date1866

Object number00029975

NameLog

MediumCopper alloy, enamel

DimensionsOverall: 430 mm, 1.1 kg

ClassificationsTools and equipment

Credit LineANMM Collection Gift from J Stanbury

Terms

DescriptionThis A2 Harpoon ship's log was designed and patented by Thomas Walker in 1866. The log is cylindrical in shape, with five fins placed around it stamped with an anchor motif and the initials 'tw'. As the log is pulled through the water, the fins turn causing a series of gears to turn. These turns are recorded and interpreted as the vessel's speed and distance travelled.HistoryA log is the name given to any device for measuring the speed of a vessel though water or the distance the vessel has sailed in a given time. Originally logs were simple affairs, but with the growth of sea-borne trade in the 17th and 18th century the need for more accurate measurements of a ships speed became more widespread. A name synonymous with the development of the log is Thomas Walker (1805 - 1873), an English clockmaker. In 1850 Walker commenced working for his uncle under Edward Massey making logs and sounders under his uncle’s patent. In 1861 Walker founded a company with his son Alexander and patented a revolutionary mechanical ship's log called the Harpoon, which incorporated the dials into the outer casing of the rotor. In 1863, a new model, the A1 Harpoon, was produced soon to be followed by the A2 Harpoon in 1866. Although very popular and robust, few examples of the Walker A2 Harpoon log are known. This is probably due to the invention of the Traffail log by Walker and Son in 1879, which allowed readings to be taken without the removal of the log from the water and superseded all the harpoon-type logs.SignificanceThis is a rare example of the revolutionary Harpoon log, which ensured accurate measurements of a ship's speed and distance travelled in the mid-19th century.