TRANSACTIONS OF TIIE SECTIONS. 
569 
in the Memoirs of the Count cle Forbin, and noticed in the Phi¬ 
losophical Transactions. “ In the night,” says the author of 
these Memoirs, “ it became extremely dark, and it thundered 
and lightened fearfully. As we were threatened with the ship 
being torn to pieces, 1 ordered the sails to be taken in; we saw 
upon different parts of the ship, above thirty St. Helmos fires; 
amongst the rest was one upon the top of the vane of the main¬ 
mast, more than a foot and a half in height. I ordered one of 
the sailors to take the vane down ; but scarcely had he taken 
th e vane from its place, when the fire fixed itself upon the top 
of the mainmast, from which it was impossible to remove it. 
Lecture on Electro-Magnetism. By W. Sturgeon. 
Mr. W. Sturgeon illustrated by experiments the progress of 
discovery in developing the magnetic energies of galvanic cur¬ 
rents of electricity, and the various means which have been em¬ 
ployed for exalting the powers of ferro-electro-magnets. He 
stated the reasons that had induced him, in 1824, to substitute 
soft iron for steel, which had been previously employed in these 
arrangements,—a substitution which atonce increasesthe energy 
and varies the character of the phenomena ; he also showed the 
method which he had adopted of exalting the power of the 
electro-magnet by bending the iron into the horse-shoe form. 
He alluded to the experiments of Professor Moll, who employed 
larger pieces of iron, one of which, with the aid of a powerful 
galvanic battery, supported 160 lbs. The American philoso¬ 
phers made the next improvement, by greatly multiplying the 
number of coils of wire round a very large mass of iron, by 
means of which they were enabled to command a power which 
lifted 2000 lbs. Mr. Sturgeon exhibited two electro-magnets, 
which he had himself constructed : one of these, the iron of 
which weighs 4 oz., furnished with 6 coils of copper wire, will 
support about 50 lbs.; the other, of which the iron weighs 
16 lbs., will support about 400 lbs. The latter is surrounded by 
20 coils of copper wire, separated from each other by pieces of 
calico. The coiling of each wire proceeds from one of the poles 
to the other, without interruption, so that all of them terminate 
at the poles. No electro-magnets, he said, have been made in 
this country possessing greater proportional powers ; a cylin- 
dric galvanic pair of plates, which can be placed in a half-pint 
pot, is sufficiently powerful to excite the largest of Mr. Stur¬ 
geon’s magnets to its maximum of polar force. 
