J. LeConte on the aiid in Florida. 9 
tended at E and E’, would be wholly i inapprecia 
The rigorous fae Bs of this problem in BEF optics, in- 
volves the application of that refined physico- ~mathapaasl | rea- 
Herschel shows, that sain the aes surface is — ee 
the refraction is made from a denser into a rarer medium, as from 
water into air,.* esi Lhiacaustic curve is the evolute of an —— 
exaggeration and distortion which ‘submerged obj ects geo 
when viewed by the eye placed in various ieaeoes above the 
plane refracting medium, 
Thus, it has been shown, that all of the beautiful optical phe- 
nomena presented by the Silver- a are referable to recognized 
physical principles, and that all of the so-called le as os 
its waters vanish under the rite of exact science. It only 
remains to indicate the causes which produce the oon 
transparency of the water, upon which, as has been shown, the 
piston summer rains oceur, the waters of thi, stream. shou 
rendered turbid by the surface drainage. But the: 
Y vanishes, when we consider the peculiar charac 
drainage of this section of Florida. Although the su 
* ae Herschel’s Treatise on Light, een Article 
‘tee Ms. ag as nde ane toeuodas von F. ee 
et 4. 
jin iting eget 0 
indensee: 
