1. Cf. the interesting remarks on this subject by Professor A. N. Garvan, of the University of Pennyslvania, in his paper, “Slide rule and sector: A study in science, technology and society”, read at the Xth International Congress of the History of Science, Ithaca, 1962 (as yet unpublished; I am indebted to Lieut. Commander D. W. Waters of the National Maritime Museum, Greenwich, for lending me a typescript of this paper).
2. The astrolabe, made in 1559 by Thomas Gemini (fl. 1524–62; Taylor [1], 165–6, Michel [14]; see also n. 24 below), and some of the instruments by Elias Allen (fl. 1606–54; Taylor [1], 198) were presented to the University of Oxford by John Greaves' brother, Nicholas, in 1659; they are now in the Museum of the History of Science, Oxford. See Gunther [5] and [6], and Birch Thomas (ed.). Miscellaneous works of Mr. John Greaves …, 2 vols. (London, 1737) ii, 371.
3. It is often forgotten that sundials continued to be important instruments long after clocks and watches had come into general use. Cf. for instance, Emerson W., Dialling. Or the art of drawing dials on all sorts of planes whatsoever (London 1770), p. iii: “And tho' we be furnished with some sorts of moving machines … as clocks and watches; yet these are often out of order, apt to stop and go wrong, and therefore require frequently to be regulated and set right, by some unerring instrument as a dial; which being rightly constructed, will always (when the sun shines) tell us truth. And therefore whether we have any clocks or not, we should never be without a dial”.