Observations relating to the Figure of the Earth. 119 
already seen, that here its soLVENT as well as attractive pro- 
perties are exerted and employed. In galvanism, the excitation 
of this power, I repeat, depends on the alternate arrangement 
of dissimilar metals having a fluid interposed between them, for 
which the one metal has a greater affinity than the other, so that 
chemical changes are the consequence: the fluid is decom- 
posed, and the products assume the gaseous form; a demand is 
made on this grand agent, in order to dissolve and support these 
new forms of existence, which are thus produced*. In this way 
the metal in contact becomes robbed of its natural quantity, 
and demands a fresh supply, which is no sooner received than it 
is imparted to the metal having the stronger affinity for the fluid, 
and where these changes and gaseous results require and de 
mand it. Thus a current is produced alternately positive and 
negative ; but which differs from electricity not only in the retar- 
dation these actions occasion, but in having to traverse a dif- 
ferent medium—an imperfect conducting fluid, by which the 
current has its velocity not only further retarded and broken, 
but its qualities; modified. 
All that has been now laid down will be further confirmed 
by the views we shall develop when we come to Chemical 
Affinity, Light, and Electricity; when I trust I shall satisfy the 
reader that I have not in the commencement held out more 
than I shall be able to establish, as I proceed in executing the 
task. Still, 1 trust every allowance will be made for any imper- 
fections which must necessarily be connected with the novelty of 
the views, on so extensive and so difficult a subject as that of 
not merely marking effects and phenomena, but the mode of 
operation and nature of that power which produces them. 
Colliergate, York, July 15, 1818. 
[To be continued. | 
XIX. Observations relating to the Operations undertaken to 
determine the Figure of the Earth. By M. Biot, of the 
French Academy of Sciences +. 
Wi EN about two centuries ago Galileo, on one of the towers 
of Florence, explained to a few individuals, in language almost 
mysterious, his new discoveries respecting the laws of gravitation, 
the motion of the earth, and the figure of the planets ; how lit- 
tle did he imagine that these truths, at that time so miscon- 
* It has been often explained how this power in different quantities, 
differing in every different kind of matter, produces and sustains bodies in 
all their various forms, states, and stages of existence, 
+ From the French of M. Biot. 
H 4 ceived 
