414 Scientific Intelligence. 
The following are those given hy two eminent German authorities, 
Treviranus and Krause, sheds reduced to English inches :— 
ean vo several’ Meanof eight 
authors by measures by 
be us. Krause, 
roe Inches, 
Thickness of cornea (central part,) 32 0-040 
’ Distance of first surface of lens from back surface of cornea, oles 0107 
yh eames a 0096 0083 
creates 0181 0181 
Axis of wits ian Dies a deeia eehae da i ROME Haas. pea 0548 0567 
» eye from eo — of the cornea to the retina, : 833 0°855 
Radios of tt surface of cornea, 301 0 348 
surface of le a, eswet, 3 one 0369 
5 a seco! he is 0196 0-201 
Curvature of retina near the axis, .. 0534 0°523 
re 
last column. This arises from the circumstance, that it is derived by 
calculation, for the curvature of an ellipse at the lesser axis, the two 
axes of which are alone given by Krause. Now, it is evident, that if 
we regard the lens as a whole, or even any considerable breadth of it, 
meun ra radius o curvature w ill be sensibly sao: lo fact, Krause 
ing a radius of ‘329 inc occur to me, however, that by 
taking the greatest any “of the lens, as given gee ine ter, and the 
curvature of the middle see both anterior and rior, as given by 
‘= e cated for the refractive indices of the parts of the eye, 
Bie 6 ir D. Brewster in his original paper in the Edinburgh 
ities toned. vol. i, page 44, with the exception of that 0 
the densest part of the % which is almost certainly mispri rinted. 
They are as follow :— 
Aqueous humor ; 13366 = 
Crystalline, outer ease PE SEE est ele ae eee Se 13767 . 
= Woe Conte, a aay ein eS asa ae OS 
<— coats, 1:°3990*= #2 
ae ; .. 136389 
Vitreous perenty , 13394 =f, 
Calculating from the preceding. data, with Sir D. Brewster’s indices 
of refraction, the author finds the positions of the foci, towards which 
= hn be rays falling For rays dive erging 
paraliclon the ‘from a eel 10 
cornea. pene 
After first refraction at the aqueous humor, = mi B82 1541 
After second refraction at first surface of of the == 1 260: 1-277 
After third refraction into the vitreous humor, | = 1060 1-135 
* In the Edinburgh Phil. Journ, we find. 13999, But I take ai to be a spit 
as in Sir D. Brewster's own subsequen ent writings, we always find 1°3 
