CATALOGUE. NATURE OF LIGHT. 



S25 



•]-Regner on the propagation of light. Zacli. 



Mon. coiT. VI. 348. 

 Scheele's experiments on the chemical efi'ects 



of light. Ph. M. XIII. 42. 

 Englefield onlhe separation of light and heat 



by refraction. Journ.R. I., I. Nich.8.111. 



125. 

 Wollaston on some chemical effects of light. 



Nich. VIII. 293. 



Found that invisible heat deoxidated as well as the red 

 xays. 

 Wollaston. Ph. tr. 1804. 428. 



Observes, that the crystals of palladium, and some tour- 

 malins, are of a deep red when viewed in the direction of 

 theaxis,andofayellowish green when viewed in a transverse 

 direction. Some crystals are greenish in the first direction, 

 and reddish in the second. 



Effects of light on vegetation. See Vegeta- 

 ble Physiology. 



Besides the salts of silver and the gums, the martial flow- 

 ers of sal ammoniac are much affected by light. 



See Double Refraction, Telescopes. 



When a ball 1 strikes a ball r so as to be reflected at an 



equal angle with respect to a given surface, the ball r is 



propelled in such a direction that s.al : s.aR : : r : 1. The 



, . ^ . s.(I— R) ^ ^ 2cos.(I— R) , ^ 



velocity of l is — ,..„, ; that of r, i -. I and 



s.(l+RJ r+l 



R being the angles of incidence and of refraction. Y. 



History of Optics. 

 Ph. M. XVIII. 245. 



Recorde, in 1551, mentions a wonderful glass of Roger 

 Bacon, agreeing to the description of a telescope, and pro- 

 fesses to understand its construction. 



Digges's pantometria. Lond. 1571. Ph. M. 

 XVm. 245. 

 Contains some hints of a telescope. 



Borellus de vero telescopii inventore. 4. 

 Hague, 1635. 



Derham on Gascoigne's invention of tele- 

 scopic sights. Ph. tr. 1717. XXX. 603. 



Lahire on the invention of telescopes and of 

 the micrometer. A. P. 1717. 78. 



♦Priestley's history of optics. 



Meister on the optical knowledge of the an- 

 cients. N. C. Gott. 1774. V, 141. 1775. 

 VI. 129. 



Particularly in painting. 



Pringle on the invention of the reflecting te- 

 lescope. 4. Lond. 1778. 



Account of discoveries relating to solar phos- 

 phori. T. Wedgwood. Ph. tr. 1792. 



Hind. Arch. III. gs. 



Pfleiderer attempts to show, that Descartes did not bor- 

 row his law of refraction from Snellius. 



Rochon on achromatic glasses. Gilb. IV. 



300. 

 On Hall's achromatic glasses. Ph. M. II. 



177. 

 *0n the invention of the telescope and other 



optical instruments. Ph. M. XVIII. 245. 



XIX. 6G, 176,232, 344. XX. 14. 



Dates. 



R. Bacon's magic lantern - 1252 



Spina invented spectacles at Pisa 1299 



Armati at Florence before - 1300 



Looking glasses made only at Venice 1300 



Telescopes discovered by Jansen 1590 

 A reflecting telescope mentioned by 



Eskinard - - l6l5 

 Snellius discovered the laws of refrac- 

 tion. Died - - - 1626 

 Descartes published on refraction 1629 

 Hall invented achromatic glasses 1729 

 Ritter discovered the blackening rays 1801 



