Course, speed and distance indicators, Astronomical and navigational instruments

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Mechanical log

Course, speed and distance indicators

Object details:

Object ID NAV0728
Description This instrument is designed to measure the distance covered by a ship. In this design, a brass rotor trails in the water and spins around as the boat moves along. This rotary motion is then passed through a register. Three dials marked '1/4-1', '1-10' and '10-100' give a readout of the distance travelled in nautical miles. The dials are also protected while the log is in the water by a brass swivelling cover. This form of log was patented by Edward Massey (about 1768-1852), whose name is inscribed on the converter, along with the trademark of three Ls in a triangle.
Date made circa 1830

Place made London
Credit National Maritime Museum, Greenwich, London
Materials Brass; copper; rope
Measurements Overall: 110 mm x 335 mm x 500 mm
  • Mechanical log (NAV0728)
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