m 
Natural Philosophy, — Electro-Magnetism* 
“ is intended to exert a power equal to ten horses : its generator 
(in place of a boiler) holds about eight gallons. The working 
cylinder is only eighteen inches long. The parts have been 
proved by hydraulic pressure to bear a force equal to two thou - 
sand pounds on the square inch ; but a weak part has been 
subsequently introduced into it, which shall give way at me 
thousand pounds of pressure, the engine being intended to be 
-worked by steam raised to seven hundred pounds.” 
17. Steam Ships building by Government. — Two steam-vessels 
have just been fitted out in Deptford dock-yard, one of 225, 
and another of 180 tons burthen. Other two are building, each 
of 296 tons, and 126 feet long, to be impelled by engines of 
100 horse-power. — Londm Journ. of Arts , vol. v. p. 151. 
18. Quantity of Water in the Rhine at Basle. — M. Escher 
has found, that the mean quantity of water which flows down 
the Rhine at Basle, in one year, is 1,046,768,676 cubic toises, 
of 1000 cubic feet each. 
ELECTRO-MAGNETISM. 
19. Dr SeebecFs Electro-Magnetic Experiment — Dr See- 
beck of Berlin took a bar of antimony about eight inches long, 
and half an inch thick, and connected its extremities, by twist- 
ing a piece of brass-wire round them, so as to form a loop, 
each extremity of the bar having several coils of the wire. By 
heating one of the extremities for a short time at a spirit-lamp, 
electro-magnetic phenomena were exhibited in every part of it. 
“ The brass-wire,” says the editor of the Quarterly Journal, 
who has repeated the experiment, “ is in that state which would 
be produced, by connecting its heated end with the negative pole 
of a voltaic battery, and its cold end with the positive pole.” 
20. M. Er man’s Electro- Magnetic Apparatus. — Having 
placed a watch-glass in a silver or copper crucible, and a small 
mass of zinc in the glass, he fastens a strip of zinc or of tin at 
one end to the mass of zinc, and, extending upwards and out- 
wards over a pasteboard band, in which the cup rests, it is fas- 
tened at the other end to the cup itself. A complete voltaic 
circuit being thus formed, the circuit is established, by filling 
the cup with acidulated water. If this apparatus is suspended 
by a thread, and a magnetic bar brought near it, either an at- 
