248 
analysis. In this, the structure and the 
dimensions of steam-packets are ilves- 
tigated, as also the mathematical results 
deduced by the author, and his deserip- 
tion of those of America. On the whole, 
the committee recommend to govern- 
ment to’ assist or contribute to the 
printing of the Memoir, as it has to the 
publication of several other works. 
Some experiments made in Sweden, 
by M. Lagerhielm, communicated to 
the academy by M. Olivier, ancient 
pupil of the Polytechnic School, re- 
siding in Sweden, have been submitted 
to the examen of Messrs. Girard and 
Ampére. The subject treated of is the 
draining off water, by orifices made in 
thin sides of the receptacles containing 
it. The learned, Swede proves that 
clastic fluids are, in this case, subject 
to the same laws as incompressible 
fluids, such as water. 
M. Ampére presented a continuation 
of his Memoir on the Electro-Dynamic 
Phenomena. Herein he has confirmed, 
by new experiments, certain results 
deduced from his preceding “ Formulze;” 
be has also ascertained and announced 
two new facts. 1. That a voltaic 
conductor, placed very near a metallic 
circuit inclosed (fermé) but not,com- 
municating with it, determines or draws 
an electric current to it. 2. That a 
circular conductor, forming an entire 
circumference, has no action to produce 
a revolution round ifs axis, of an in- 
closed conductor, be it of whatever 
form ; and that the same properly occurs 
in a conductor bent as the are of any 
circle, whatever be the number of de- 
grees of that arc. 
To this succeeds an investigation of 
the electric currents in the interior of 
the globe, proceeding from east to 
west, and the more intense as they are 
nearer to the magnetic equator, which 
must then be considered as a medium 
direction between all the currents; these 
‘currents are considered, in all the cir- 
cumstances of motion that they would 
produce on conductors, whether hori- 
zontal or vertical. 
The results collected, by this author, 
are conformable to the numerous expe- 
yiments already made; some by him- 
self, others by M. Delarive, all of which 
tend to shew the action that the earth 
exercises on mobile voltaic conductors. 
The. author has thus completed the 
theory of action which he had disco- 
vered between two conductors, and also 
that of the influence of the terrestrial 
Proceedings of Public Societies. 
[Oct. 1, 
globe upon a conductor; a phenomenon 
which he was the first to observe. 
In the limited state of human know- 
ledge, it is not possible to ascertain the 
distribution of the electric currents of 
our globe, nor even to decide the ques- 
tion of their actual existence. If it be 
admitted, we must’ suppose one part of 
these currents to come very near the 
surface, as the direction of the magnetic 
needle is affected by, the variations of 
the temperature from day to ‘night. 
These variations, however,being scarcely 
perceptible, it is inferred, that the effects 
depend chiefly on the cufrents that 
prevail at great depths. 
Another object of the researches of 
M. Ampére, is the assimilation that he 
makes of the magnet, and of the assem- 
blages of cireular parallel currents, to 
which he gives the name of electro- 
dynamic cylinders. This assimilation 
may be manifested, either by the way 
of experiment or by calculation. In 
employing the second method, we must 
compare the poles of the magnctised 
bars, and not their extremities, with 
the extremities of the electro dynamic 
cylinders; as, according to the experi- 
ment of M. Ampére, the magnetic poles 
disclose the same properties as the ex- 
tremities of the electro-dynamic cy- 
linders. This kind of proof, while it 
confirms the results of experiment, im- 
presses the character of theory on 
inductions derived solely from the ob- 
servation of facts. 
Two young and able naturalists have 
supplied what was wanting, in this re- 
spect, in the Tract of M. Ampére on 
the identity of magnetism and electri- 
city. Their memoirs were read to the 
academy, in the sitting of February 3, 
last. That of M. Mont. Ferrand con- 
tains calculations relative to the mutual 
action of a rectilinear-conductor, and 
of an assemblage of circular currents, 
situated in planes parallel to the di- 
rection of this conductor. Assuming 
the value or proportion assigned by 
M. Atmpére, to the action of two elc- 
ments of electrical currents, the author 
determines that which is exercised 
by an indefinite rectilinear conductor, 
1.'On an element of electrical current. 
2. On a circular current. 3. On an 
assemblage of similar currents, perpen- 
dicular to a right or curved line, passing 
through their centres. When this is a 
right line, the calculation reproduces 
the law discovered in 1820, by M. Biot; 
and confirmed by the experiments pub- 
lished, 
