Dr Latta on Ice-Bergs, 245 
bergen is very bold, and has been evidently encroached on by 
the ocean, which washes even the foot of its mountains. The ice- 
bergs, like the circumjacent coast, seem incapable to resist the fury 
of the waves. Captain Scoresby states a fact in his Essay on 
Ice-Bergs, in the Fourth Number of this Journal, which is 
against the probability of the precipitous crest facing the sea 
gaining ground ; for he remarks, The front of each ice-berg 
varies from 400 to 500 feet in height above the level of the 
ocean, lies parallel with the shore, and is generally washed by 
the sea.” Surely they would not all have their boundaries li- 
mited by the shore. Some would have made greater progress, 
and long ere now encroached on the empire of the waves. 
The general appearance of this ice-berg corresponds with all 
we saw, which were more than seven in number. They all 
occupied valleys. The hills on either side measured from 700 
to 1200 feet above the level of the sea. Ice-bergs are compos- 
ed of fresh-water they have a bluish green colour, owing to the 
obstruction and reflection of the more refrangible of the rays of 
light. When seen floating in small masses, they seem quite 
black, for then being in little pieces, and quite transparent, all 
the rays of light are transmitted. — After contemplating these 
grand objects, I returned to the ship, highly gratified with the 
magnificence of the scene. 
Art. V . — On the Phenomena of Dichroism, or the Absorption 
of Common Light by Crystallised Bodies. By David 
Brewster, LL. D. F. R. S, Lond. and Sec. R. S* Edin. 
In the course of the experiments on the absorption of polaris- 
ed light, of which an abstract was given in the last number of 
this J ournal, I had occasion to investigate the law of a very 
interesting class of phenomena, which appeared by the trans- 
mission of common light in different directions through crystal- 
lised bodies. Cordier, when he discovered the Dichroite, ob- 
served the two colours of the light which it transmitted in dif- 
ferent directions, and gave it the name of Dichroite^ (from 
^vo tzvo, and colour J, on the presumption that nature had 
