Views on the origin of Terrestrial Magnetism. 117 
ee 
° 
=} 
og 
= 
=: 
2 ad 
° 
a 
oO 
art 
te 
o 
= 
= 
oo 
OD 
“— 
*% 
a 
2 
a 
® 
o. 
te 
2 
~24 
@ 
f=] 
= 
fa) 
5 
- 
° 
o 
7 
o 
' 
ch the su h 
planets of the system. It is the hypothesis reversed of the central 
magnet, for it places in space the magnetic mass which some physicists 
have supposed to exist within the earth 
The real cause of the magnetic polarity of the planets, is in my view 
the same for all, and Arago’s experiment conducts to it in a straight 
line. It results even from the condition of their existence. Each star 
turning around a central axis, and in determinate curves, is influenced 
by the mass of these stars and their velocity at the circumference; ina 
word, the agent decomposing into two fluids the normal magnetism of 
the earth and the other planets, is their rotation. A geometer examin- 
ing this opinion, would find, we believe, that the declination, inclination 
and the perturbations of the magnetic needle, are explained on this 
hypothesis much better than on any other. 
ince my researches on circular electro-magnets and fm general on 
bodies in rotation, | have sought much for experimental demonstration 
of this theory, and have now the conviction that this is impossible, as it 
rved, it 
It to the inductive action of the earth, rendered so striking by the ex- 
periments of Arago and Mr. Barlow. 
_ Alongside of the different sources of magnetism mentioned in Trea- 
llses on Physics,—friction, pressure, percussion, torsion,—we should add 
* Poggendorff’s Annalen, iv, 1. 
t See Proceedings, Brit. Assoc. 1853, Sept. 7, Report of Col. Sabine, 
’ } Sur la chute dune bolide par M. N. Nicklés and J. Nickiés, Compt. Rend. de 
l'Acad,, xix, 1035. “ss 
