208 Hastings — Optical Constants of the Human Eye. 



Table I. 





Curvature of incident wave-surface 



Curvature of the cornea 

 Curvature of the first lens surface 

 Curvature of the second lens surface 

 Distance from vertex of cornea 

 to first lens surface 

 to second lens surface 

 to first principle focus 

 to second principle focus 

 to first principle point 

 to second principle point 

 to first nodal point 

 to second nodal point 





c' = -0000 



c' =-0-0100 



c' = -0-0330 



c'=-0 0660 





X 



dx 



7 



1-2773 









V 



1-0000 



•1043 



•3433 



•6690 



n 



y 



-1-6667 



-•0239 



-•0746 



-•1520 



d 



•360 



-•0060 



-•0200 



-•0400 



tV 



•720 









F, 



-1-3744 



•0279 



•0873 



•1618 



F, 



2-2823 



-•0316 



-•0995 



-•1876 



P, 



•1753 



; 0021 



•0063 



•0105 



V, 



•2110 



•002.9 



•0087 



'0146 



n y 



•6969 



-•0066 



-•0210 



-•0404 



n n 



•7325 



-•0057 



-•0186 



-•0363 



of distinct vision measured from the vertex of the cornea, 

 which is taken as the origin of abscissas. The curvature of 

 the cornea and the position of the second vertex of the lens 

 are invariable. 



For the chromatic differences for these constants we find the 



}wii 



ag table : 



Table II. 



dx/Sn 







X 



c' = -0000 



c' = - -0100 



c' = - -0330 



c' = - -0660 



B\ 



+ 5-660 



+ 5-593 



+ 5-464 



+ 5-283 



F„ 



— 5-504 



-5-448 



— 5-342 



— 5-182 



P^ 



+ 0-175 



+ 0-167 



+ 0*158 



+ 0-152 



P-, 



+ 0-335 



+ 0-335 



+ 0-331 



+ 0-329 



n i 



— 0-179 



— 0-190 



— 0-211 



— 0-228 



n. 



— 0-019 



— 0-022 



— 0-038 



-0-051 



With these two tables it is easy to solve all problems con- 

 nected with the purely optical properties of the schematic eye. 

 We may, for example, employ them for comparing the per- 

 formance of the model with any recorded observation on real 

 eyes. Thus Helmholtz (page 158) states that for his eye the 

 difference of accommodation for red (C) and violet (G) light 

 was -0167, in the units employed in the tables, while Fraun- 

 hofer, who gave the first recorded measures involving this mag- 

 nitude, found a value included between -0154 and *0205. The 

 schematic eye as described in this paper demands '0167. 



After all the above calculations were concluded I found a 

 series of observations on his own eye by Max Wolf* which 

 might have been used as well as the ones given above. His 

 method was to observe a small globule of mercury, strongly 



* Armalen d. Physik u. Chemie, xxxiii, 1888. 



