} 
British Association for the Advancement of Science. 293 
polarity above mentioned. The reason of this is, that the more 
or less refrangible sides of the rays lie in every direction; but as © 
‘soon as these sides are arranged in-the same direction by pris- 
matic refraction or by. diffraction, the light displays- the same 
properties as if it had originally formed part of a spectrum. 
Some discussion among” the wee on points connected —_ 
this subject, ensue 
_~ Sir Wm. R: Hiunfiton then made a Per cg respecting 
the propagation of light in vacuo; and subsequently, on the 
propagation of lizht in crystals. The object of these papers 
was to advance the state of our knowledge respecting ‘the law 
which regulates the attractions or repulsions of the particles of 
~ the ether on each other. 
Sir J. Herschel offered a Note on the Structure of the Vitreous 
Humor of the Eye of a Shark. . The-result is, that the vitreous 
humor, (so called,) of this fish is no jelly, but simply a clear li- 
quid; inclosed in some close’ cellular structure of transparent 
membranous bags, which, by their obstruction to the free move- 
ments of the contained liquid, imitate the gelatinous state. 
Mr. Ball, of C. C. Cambridge, read a paper “ On the meaning 
of the Arithmetical Symbols for Zero and Unity, when used in 
: atcagend Symbolical Algebra.” . 
- A communication was read from Prof. Wolisih, “On Sibdeien: 
~nean Temperature ; and notice of a Brine Spring emitting Car-— 
bonic Acid Gas.” Observations had been made and were now 
~ in progress, on the temperature of the earth at various distances 
beneath the surface, in the vicinity of Edinburgh, the results of 
which he intended to lay before the next meeting of the Associ- 
ation. ‘The brine spring is about a mile from Kissingen, Bava- 
tia. It has 3 per cent of salt, and rises in a bore 325 Bavarian 
_ feet deep in red sandstone; but it is understood that the water 
flows at about 200 feet in deyeh: Its temperature is never less 
than 65°,—the mean temperature of springs.near, being only 50° 
to 62°.- It discharges carbonic acid gas in volumes almost unex- 
ampled, keeping the water,—in a shaft of eight feet diameter,—in 
a state resembling. turbulent ebullition. 'The enormons supply of 
gas has led to its use in gas. baths, for which purpose it i8 carried 
off by a tube connected with a huge inverted funnel, which rests 
upon the water. It contains scarcely a trace of nitrogen. It is 
conducted into chambers properly prepared and thence into baths, 
