C 494 3 
XXX. Ow electrical and magnetic rotations. By Charles 
Babbage, Esq. F. R. S. &c. &c. Communicated May 29, 1826. 
Read June 15, 182 6. 
The known fact, that artificial magnets receive additional 
increments to their power by slowly adding weight to the 
load they support, combined with the circumstance, that 
pieces of iron or steel exposed to the influence of a magnet, 
neither acquire nor lose their magnetism instantaneously, led 
me to explain Mr. Barlow’s experiments “ On the temporary 
magnetic effect induced in iron bodies by rotation,” * without 
having recourse to any new property of matter, and to apply 
the same consideration of the time of acquiring and losing 
magnetic virtue to the curious experiments of M. Arago. 
These views are stated in a paper printed in the Phil. Trans, 
for 1825, which contains the observations that occurred to 
Mr. Herschel and myself, in repeating and varying those 
experiments. 
As the explanation there given is intimately connected 
with the experiments detailed in the present paper, and 
as they were undertaken with a view of giving additional 
evidence to the principle to which I have alluded, I shall 
here briefly re-state the manner in which time influences 
the results of certain magnetic phenomena, whose produc- 
tion depends on the application of motion to some part of 
the apparatus employed. 
* Phil. Trans. 1825. 
