to the end of his life was the best method of finding the longitude at sea (ib. p. 246).
Wren's inaugural oration addressed to the members of Gresham College in 1657 comprises many subjects which still occupy the attention of scientific men. In this address, after a short exordium, he calls in astronomy in aid of theology, mentioning the unsatisfactory explanations given by theologians of the three days and nights during which our Lord rested in the grave. ‘Here,’ he said, ‘seems to be need of an astronomer, who thus possibly may explain it. While there was made by the motion of the sun a day and two nights in the hemisphere of Judea, and at the same time in the contrary hemisphere was made a day and two nights;’ observing that ‘Christ suffered not for Judea alone, but for the whole earth.’ He also explained the retrocession of the shadow on the dial of Ahaz (2 Kings xx. 11) to be the effect of a parhelion, adding that we need not fear to diminish a miracle by explaining it. He then spoke of the enormous distance of the nearest fixed star, ‘and yet probably some are infinitely more remote than others.’ He held out the expectation that some one of that age would explain Kepler's elliptical theory of the planetary orbits. This was said nearly thirty years before the publication of the ‘Principia;’ but Newton himself allows (Principia, Scholium to Prop. iv. B 1) that Wren, Hooke, and Halley had already arrived at the law of the inverse square. The demonstration, however, of this law was reserved for Newton. Wren speaks with natural enthusiasm of the revelations, then comparatively new, afforded by the telescope—of the physical nature of the sun, his spots and faculæ, of the planets and the moon ‘who to discover our longitudes by eclipsing the sun hath painted out the countries upon our globe with her conical shadow as with a pencil.’ He mentions magnetics as a British invention (that refers, however, to the inclination and the variation of the needle, not the discovery of the compass), and to logarithms as wholly a British art [see Napier, John, 1550–1617]. The Latin oration as delivered is published in Ward's ‘Lives;’ the English draft in the ‘Parentalia’ (p. 200). Both are given by Elmes (App. p. 27). The art of engraving in mezzotint, which is often said to have owed its origin to Wren about this time, seems to have been solely the invention of Ludwig von Siegen, who imparted his secret to Prince Rupert, and the prince was apparently the first to practise the art in England (Parentalia, p. 214; cf. art. Rupert, ad fin.)
Wren took no small part in the formation of the Royal Society. According to a letter of Dr. Wallis, quoted in the recently published ‘Records of the Royal Society’ (1897): ‘About the year 1645 there had sprung up an association of certain worthy persons inquisitive in natural philosophy who met together first in London for the investigation of what was called “the new or experimental philosophy;” and afterwards several of the more influential of the members about 1648 or 1649, finding London too much distracted by civil commotions, commenced holding their meetings at Oxford.’ One of these was Dr. Wilkins, the master of Wren's college. At first the meetings were held at Wilkins's college during Wren's residence there. When Wilkins was appointed to Trinity College, Cambridge, the meetings were continued in the rooms of Robert Boyle [q. v.], with whom Wren was intimate, and he took no small part in their discussions and experiments. The associates occasionally combined their gatherings with those friends who still remained in London, and the usual place of meeting was Gresham College, in Wren's private room on the days of his lectures. During one of the four years of Wren's professoriate, viz. 1659, these lectures were interrupted in consequence of civic troubles, but were resumed after the king's restoration. After one of these meetings (28 Nov. 1660) the determination was reached to ask the king to erect the association into a permanent society by royal charter. The king's approval was reported to them on 5 Dec. of the same year, and they then proceeded to complete the arrangements, and the drawing up of the preamble of the charter, of which a draft copy has been handed down, was entrusted to Wren (ib. p. 196). After this Wren was most constant in his attendance at the meetings for more than twenty years, until his architectural business absolutely precluded it. He was president of the society from 1680 to 1682 inclusive. After 1665, however, his original communications to the society became comparatively rare.
At the opening of a new year, soon after the establishment of the Royal Society—and probably 1664—he gave an address stating the objects to which he recommended the society to devote its energies. He classed these under three heads, viz.: knowledge, profit, and convenience of life. The heads of this discourse embrace—punctual diary on meteorology; the study of refractions; the tremulation of the air meteors and the inquiry if anything falls from them; the growth of fruits and grain, plenty, scarcity, and the
