Steam-Engines.—Scientific Researches in Brasil. 318 
The ice which obstructs the navigation of the arctic seas con- 
sists of two very different kinds; the one produced by the con- 
gelation of fresh, and the other by that of salt water. In those 
inhospitable tracts, the snow which annually falls on the islands 
or continents, being again dissolved by the progress of the sum- 
mer’s heat, pours forth numerous rills of limpid streams, which 
collect along the indented shores, and in the deep bays inclosed 
by precipitous rocks. ‘There, this clear and gelid water soon 
freezes, and every successive year supplies an additional invest- 
ing crust, till, after the lapse of several centuries, the icy mass 
rises, at least to the size and aspect of a mountain, commensurate 
with the elevation of the adjoining cliffs. The melting of the 
snow, which is afterwards deposited on such enormous blocks, 
likewise contributes to their growth; and by filling up the acci- 
dental holes or crevices, it renders the whole structure compact 
and uniform. Meanwhile, the principle of destruction has al- 
ready begun its operations. The ceaseless agitation of the sea 
gradually wears and undermines the base of the icy mountain, 
till at length, by the action of its own accumulated weight, when 
it has perhaps attained an altitude of a thousand or even two 
thousand feet, it is torn from its frozen chains, and precipitated 
with a tremendous plunge into the abyss below. This mighty 
launch now floats like a lofty island on the ocean, till, driven, 
southward by winds and currents, it insensibly wastes and dis- 
solves away in the wide Atlantic. 
STEAM ENGINES IN CORNWALL. 
From Messrs. Leans’ Report for September 1818, it appears 
that the following was the work performed during that month, 
by the engines reported, with each bushel of coals. 
Pounds of water lifted | Load per square 
1 foot high with each bushel.) inch in cylinder. 
23 common enginesaveraged 23,009,446 various. 
Woolt’s at Wheal Vor a'as) 22090 h45808 17°8 lib. 
Ditto Wh. Abraham .. 47,540,653 | . 16°8 
Ditto Pitts, nee Sense lyase l 6°7 
Wheal Abraham engine .. 36,753,403 10:9 
United Mines ditto -. 39,608,998 18-7 
Treskirby ditto .. .- 37,320,477 10-8 
Wheal Chance ditto peau Gl Zsh72 11-9 
SCIENTIFIC RESEARCHES IN BRASIL. 
Mr. William Swainson, F.L.S. has just returned to this coun- 
try from Brasil. He quitted England in the autumn of 1816, for 
the sole purpose of exploring that distant country, and collecting 
its splendid and extraordinary productions. Mr. S. proceeded 
in 
