HISTORICAL BIBLIOGRAPHY 703 



Werner discusses the claims of Da Vinci, (1500), and of Levi ben Gerson, 



1321-1344. Wiedemann (which see) refers hack to Ibn al Haitem, about 



1039. 

 Young, Thomas. On the Mechanism of the Eye. Read before the R. S., 



Nov. 27, 1800. In the transactions of the R. S., 1801, pp. 23-88. On pp. 



39-40 he describes astigmatism and shows that it can be corrected by making 



the spectacles oblique, p. 43. See also Airy. On pp. 57-58 is described a 



decisive experiment to show that the accommodation of the eye is due to a 



change in the crystalline lens. 

 Wilde, Dr. Emil. Geschichte der Optik vom Ursprunge dieser Wissenschaft 



bis auf die gegenwartige Zeit. 2 parts. I, 3,52 p., 3 p., II, 407, p., 4 pi. 



Rucker und Puchler, Berlin. Part I, 1838; Part II, 1843. 

 Zahn, Joannes. Oculus artificialis teledioptricus, sive telescopium nora 



methode explicatum ac comprismis e triplici fundament o physico seu 



naturali, mathematica dioptrico et mechanico, seu practice stabilitum; 



opus curiosum theorico-practicum magna rerum varietate adornatum. 



2d ed. 50 + 645 + 15 P- over 600 fig. Johannis Christophorilochneri, 



Norimbergae, 1702. 



