Catalogue Entry: OTHE00100
Chapter V
[1] Optics, Prop. vii., Book ii., p. 91. In his reply to Hooke, who justly "reprehended him for laying aside the thoughts of improving optics by refractions," he seems to modify his opinion by saying that he tried what might be done "by two or more glasses or crystals, with water or some other fluid between them." "But what the results by theory or by trials have been, he might possibly find a more proper occasion to declare." This was written in 1672, and we can therefore say with certainty that he failed in this attempt, as it was in 1684 that he pronounced the case to be desperate. It is a curious circumstance that David Gregory, in his Lectures delivered in Edinburgh in 1684, suggests that, in imitation of the human eye, the {object-glasses} of telescopes might be composed of media of different density. In Brown's translation of Gregory, the sense of the passage is not brought out. See Gregory's Catoptries, Prop. xxiv., Schol., pp. 110, 111.
[2] See Tilloch's Philosophical Magazine, Nov. 1798, vol. ii. p. 177{,}
[3] See my Treatise on Optics, new edit., p. 506.
[4] Optics, Part, ii., Prop. iii., p. 110.
[5] Edinburgh Transactions, 1831, xii. p. 124.
[6] Phil. Mag. vol. xxx. p. 73.
[7] Bibl. Univers. Août 1847.
[8] Silliman'sJournal, vol. iv. p. 388. 1847.
[9] Hist. of Inductive Sciences, vol. ii. p. 361; and Edinburgh Review, vol. lxvi. p. 136, and vol. lxxiv. p. 288.
[10] Répetoire d'Optique, tom. ii. p. 459.
[11] Poggendorff's Annalen. 1852, No. 8.
[12] Ann. de Chim. et de Phys. tom xxxv. p. 385 &c.
[13] The changes of colour in the spectrum at different seasons of the year, and the different hours of the day, and when formed from different portions of the illuminated sky, as well as from the direct light of the sun, are very remarkable. We have mentioned one or two of them in the Edinburgh Review, vol. lxxiv. p. 284, Jan. 1842. One of these observations is as follows: — "October 23, 1832. 11th, The yellow comes distinctly up to F, and a little beyond it; i.e., the blue has been all absorbed in the green space of Fraunhofer's spectrum from E to F." In another observation on the 5th February 1833, the green space was wholly yellow.
[14] Letter to Oldenburg, Feb. 6, 1672, in Phil. Trans. No. 80, p. 3081, § 3.
[15] Phil. Trans. 1852.
[16] See my Treatise on Optics, new edition, pp. 182, 183.
