408 Description and Use of the Apparatus employed 
scribed, but it will only be represented in the figures j and not 
again alluded to. 
If the conductor CD, instead of moving parallel to AB, should 
be made to turn in a parallel plane, and form all angles with AD, 
the two crossing one another at their middle points, then the two 
halves of each conductor will attract and repel one another, ac- 
cording as the currents are in the same or in opposite directions ; 
and consequently CD will turn till it has arrived in a situation 
parallel to AB, when the currents will have the same direction. 
Hence, it follows, that in the mutual action of two electrical 
currents, the directive action, as well as the attractive and re- 
pulsive ones, depend on the same principle, and are only diffe- 
rent effects of one and the same action. 
M. Ampere now proceeds to examine the mutual action be- 
tween an electric current and the terrestrial globe, or a magnet, 
as well as that of two magnets on one another, and he shews that 
they are all referable to the law of two electrical currents, by 
conceiving on the surface and in the interior of a loadstone, as 
many electrical currents in planes perpendicular to the axis of 
the loadstone, as we can conceive lines forming without inter- 
sections shut curves. He concludes, therefore, that the pheno- 
mena of the loadstone are produced solely hy electricity^ and that 
there is no other difference between the two poles fa loadstone hut 
their position with regard to the currents of which the loadstone 
consists^ so that the south pole is that which is found to the 
Hght of the currents^ aiid the north pole that which is found 
to the I ft. 
In the apparatus shewn in Fig. 2. of PI. VIII. the electrical 
current arriving by the support CA, runs along the conductor 
AB, and redescends by BDE. The pivot of a glass axis HG 
turns in the steel cup F, containing a globule of mercury, and 
the current is communicated from DF to the copper box I, and 
to the conductor KLMNOPQ, whose extremity Q is immersed 
in mercury, communicating with the other extremity of the pile. 
Things being thus arranged, and the conductor LN resting, as 
in the figure, against the stop T of the fixed conductor CABDF, 
the current in MN will be contrary to that of AB ; whereas by 
turning KLMNOPQ round a semicircle, the two currents will 
be in the same direction. The following effect was now pro 
