Note 9 — The First Self-Registering Instruments

William Derham, Philosophical Experiments and Observations of ... Dr. Robert Hooke, London, 1726, pp. 41-42 (reprinted in Gunther, op. cit. footnote 8, vol. 7, pp. 519-520). This description, dated December 5, 1678, predates the Royal Society's request for a description (Gunther, op. cit. footnote 8, p. 656) by four months, but the Society no longer has any description of the clock. As to the actual completion of the clock, the president of the Society visited "Mr. Hooke's turret" to see it in January of 1678/79 but it was not reported "ready to be shown" until the following May (Gunther, pp. 506, 518).