U. S. patent 204400.
U. S. National Museum cat. no. 248691.
U. S. patent 204400. The text of this patent speaks of dividing the second into “halves, quarters, eighths, etc.” and in the summation of claims of “an escape wheel, A, provided with one or more pairs of pins...” showing that measuring tenths of a second with a five-pin escape wheel was not conceived at this time. It is interesting to note that in referring to the drawings shown in figure [12] the text states “In the present instance two pairs of pins are used to denote quarter seconds.” Only one pair of pins is shown, which is correct. This seems, however, to reflect carelessness on the part of patent attorneys and examiners, as the error exists in the original manuscript patent application preserved in the National Archives, Washington, D. C.
U. S. patent 216917, issued to William A. Wales and assigned to William B. Fowle, was applied for on November 1, 1878, after the device was already in use on earlier specimens of these watches.
The mechanism was also covered by British patent 3893, issued September 27, 1879, to Philip Syng Justice on behalf of William B. Fowle.