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Massey patent ship's log

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Massey patent ship's log
Smithsonian Institution, Photo by Richard Strauss, Negative #: 2009-9710


This object appears in the following sections:

Marine Patent Models — Complete Catalog: 1876-1880

Marine Patent Models — Steering the Way

Massey's patent ship's log
Massey's patent ship's log

Massey's patent ship's log
Massey's patent ship's log

Ship's log
Catalog #: 309,317, Accession #: 89,797
In collection
From the Smithsonian Collection

This two-part mechanical log measures a vessel's speed though the water. The four-bladed rotator is towed astern and registers the distance traveled and speed on an integral dial. Closer to the ship, or even mounted to the ship's rail, a second mechanism measures rotations of the towing rope to record the same information. The rotator must be hauled in to be read, but the second log can be monitored while the first is still in operation. This high-quality working example was submitted to the U.S. Patent Office when John Edward Massey, its British inventor, applied for a patent in 1877.

Date Made:
Transfer from the U.S. Patent Office

Since the sixteenth century, sailors had determined vessel speed using a log. This device was basically a rope with knots tied at intervals along its length. With a board attached to one end to create drag, the log-line would be heaved overboard and allowed to run out for a short period of time. The number of knots counted off during that time indicated the speed. (The unit of speed at sea is therefore the knot, one knot being equal to one nautical mile per hour). Logs provided vital information for navigation but were susceptible to a variety of errors, and inventors in the seventeenth and eighteenth centuries sought ways to improve their accuracy. Edward Massey, a leading London nautical instrument maker, received the first patent for a successful mechanical log (British patent 2,601, March 24, 1802), and many ships used his firm's "patent logs" throughout the nineteenth century. John Edward Massey inherited the business and continued to patent improvements to his father's work.


Willem F. J. Morzer Bruyns, Elements of Navigation in the Collection of the Mariners' Museum (Newport News, 1996), 62-63.

John Edward Massey, Ship's Log, U.S. patent no. 206,682, Aug. 6, 1878.

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