ower
of such metals as silver, copper, &c. &c., inasmuch as in the iron by far
the greater part of the effect is due to what may be called ordinary
magnetic action. There can be no doubt that the cause assigned by Messrs.
Babbage and Herschel in explication of Arago's phenomena is the true one,
when iron is the metal used.

139. The very feeble powers which were found by those philosophers to
belong to bismuth and antimony, when moving, of affecting the suspended
magnet, and which has been confirmed by Mr. Harris, seem at first
disproportionate to their conducting powers; whether it be so or not must
be decided by future experiment (73.)[A]. These metals are highly
crystalline, and probably conduct electricity with different degrees of
facility in different directions; and it is not unlikely that where a mass
is made up of a number of crystals heterogeneously associated, an effect
approaching to that of actual division may occur (127.); or the currents of
electricity may become more suddenly deflected at the confines of similar
crystalline arrangements, and so be more readily and completely discharged
within the mass.

[A] I have since been able to explain these differences, and prove,
with several metals, that the effect is in the order of the conducting
power; for I have been able to obtain, by magneto-electric induction,
currents of electricity which are proportionate in strength to the
conducting power of the bodies experimented with (211.).

S. _Royal Institution, November 1831._

_Note._--In consequence of the long period which has intervened between the
reading and printing of the foregoing paper, accounts of the experiments
have been dispersed, and, through a letter of my own to M. Hachette, have
reached France and Italy. That letter was translated (with some errors),
and read to the Academy of Sciences at Paris, 26th December, 1831. A copy
of it in _Le Temps_ of the 28th December quickly reached Signor Nobili,
who, with Signor Antinori, immediately experimented upon the subject, and
obtained many of the results mentioned in my letter; others they could not
obtain or understand, because of the brevity of my account. These results
by Signori Nobili and Antinori have been embodied in a paper dated 31st
January 1832, and printed and published in the number of the _Antologia_
dated November 1831 (according at least to the copy of the paper kindly
sent me by Signor Nobili). It is evident the work could n