John Edward Massey of England submitted this model to the U.S. Patent Office in 1877, along with his application for a new ship’s log. The Patent Office transferred it to the Smithsonian in 1926. One feature of Massey’s patent was an improved connection between the register and the rotator of a taffrail log. Another was a ceramic dial with two concentric circles, each read by a separate hand. In this example (which is not a taffrail log) the outer circle is marked "ONE MILE CIRCLE OF SIXTY PARTS" while the inner circle is graduated to 100 parts and marked "NAUTICAL MILES." A separate part of this instrument is a mechanical log with a ceramic dial with two concentric circles, each read by a separate hand. Here the outer circle is marked "ONE MILE CIRCLE OF SIXTY PARTS" while the inner circle, graduated to 100 parts, is marked "NAUTICAL MILES."
Ref: J. E. Massey, "Ship’s Log," U.S. patent #206,682 (1878).
