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Ordinary Meeting, February 19th, 1867. 
J. P. Joule, LL.D., F.RS., &c., Vice-President, in the Chair. 
Mr. Sidebotham inquired whether any member was 
acquainted with the particulars of a remarkable discovery 
in connection with the conversion of dynamical into elec- 
trical force, by M. Siemens and Dr. Wheatstone, a brief 
notice of which appeared in the Athenceum of Feb. 16. 
Mr. Wilde said, that he happened to be present at the 
meeting of the Royal Society on the 14th inst., when M. 
Siemens’ interesting paper “On the Conversion of Dynamical 
into Electrical Force, without the aid of Permanent Mag- 
netism,” was read. The apparatus used in his experiments, 
and exhibited at the meeting, consisted of two electro- 
magnets, coiled with long and thin wires, and between the 
poles of these electro-magnets an armature, also coiled with 
long and thin wires, was made to revolve rapidly by means 
of pulleys. 
When a voltaic battery was connected with the wires of 
the electro-magnet for a few moments, and afterwards dis- 
connected, the residual, or permanent, magnetism of the 
electro-magnets was sufficiently strong to generate a feeble 
current of electricity in the wire of the revolving armature. 
The feeble current thus generated was then transmitted 
through the coils of its own exciting electro-magnet, instead 
of the current from the battery, and by the mutual action 
and reaction of the electro-magnet and the armature upon 
each other, the magnetism of the machine could be exalted 
to such a degree as to require the application of very con- 
siderable power to drive the apparatus. 
Proceedings— Lit, & Tail, Society.— Yoe. YI No. 11— Session 1866-Y 
