iM Hints for the Formation of 
No. 57* 
Jlgenda, or a Collection of Observations and Hesear - 
ches ? the Results of which may serve as the Foundation 
for a Theory of the Earth. By M. De Saussure. 
(Concluded from page 343.) 
CIIAP. XXI. 
Researches to be made in regard to the Loadstone . 
1. THE theory of the loadstone ought to form a part 
of the theory of the earth, because the phenomena which 
depend on it belong to the whole globe ; and because 
Halley, and after him other philosophers, have endea- 
voured to explain the different phenomena of the magnet 
by supposing the earth to be hollow, and that it contains 
in its cavity one or more magnetic globes. 
2. In considering the loadstone it ought first to be exa- 
mined whether, in order to explain its phenomena, we 
ought, like Descartes, to suppose a close fiuid moving in 
a vortex around the magnet, and entering at one of its 
poles and issuing at the other : or, as M. JEpinus, a dis- 
crete fluid, susceptible of rarefaction and condensation* 
which is rarefied in one of the poles and condensed in the 
other ; or, lastly, as M. Prevost*, two fluids, susceptible 
of being combined with each other in such a manner that 
one of them alone is acccumulated around the north pole 
of a magnet, while the other is accumulated around the 
south pole ; and that all the magnetic, phenomena may be' 
explained by the elective attractions which these fluids 
exercise either upon each other or on ironf. 
* De l’origine des forces m ago etiqu.es, 8. Geneve 1788. 
f The celebrated Coulomb admits also two fluids, which compose the magne- 
tic fluid, and which exercise their action in the inverse ratio of the square of the 
distance : but, in the theory of phenomena connected with the action of the globe, 
this philosopher sets out from certain facts immediately given by observation ; 
one of which it would be of importance to verify in different points of the globe. 
This fact is, that the forces which attract one of the poles of a magnetic needle 
