386 Miseellanies. 
was equal to the report of a pistol, and the boiler*was projected with 
violence against the wall of the building. It follows from hence, 
that if it be admitted that the temperature of water placed in a vessel, 
heated to redness, is less than 100° R., it is necessary to admit also 
that in the preceding experiment, the water, which, before the boiler 
had arrived to redness, had attained a high temperature, was cooled 
afterwards to below 100°, when the boiler had reached-the tempera- 
ture of redness, although in this case there had not been any notable 
loss of steam ter a great number of other experiments, M. Le- 
chevalier nciisbadind that the temperature of water, heated in an in- 
candescent vessel is always less than 100°; that, accordingly, the 
principle of the equilibrium of temperature in a confined space, which 
has heretofore been considered as fundamental in the theory of heat, — 
cannot any longer be admitted ; and that this principle is liable to ex- 
ceptions in particular cases.— Revue Médicale, Sept. 1830. 
The conversion of magnetism into electricity.—This long 
wished for result has at length been obtained by Mr. Faraday. Jf 
two wires, A and B, be placed side by side, but not in contact, and 
a voltaic current be passed through A, there is instantly a current 
produced, by induction, in B, in the opposite direction. Although 
the principal current in A be continued, still the secondary current 
in B is not found to accompany it; for it ceases after the first moment; 
but when ‘the principal current is stopped, then there is a second 
current produced in B, in the opposite direction to that of the first, 
produced by the inductive action, or in the same direction as that of 
the principal current. These induced currents are so momentary 
that their effect on the galvanometer is scarcely sensible ; but when 
they are passed through helices containing unmagnetized steel nee- 
dles, they convert them into magnets. : 
If a wire, connected at both extremities with a galvanometer, be 
- coiled, ‘in the form of a helix, round a magnet, no current of elec- 
tricity takes place init. This is an experiment which has been made 
hundreds of times by various persons, in the hope of evolving elec- 
tricity from magnetism. But if the magnet be withdrawn, or intro- 
duced into such a helix, a current of electricity is produced whilst 
the magnet is in motion, and is rendered evident by the deflection of 
the galvanometer. If a single wire be passed by a magnetic pole, 
a current of electricity is induced through it, which can be rendere 
