TO THE MOVEMENT OF MACHINES. 5Q7 
helix in which a magnet is inserted. This is the explanation of the 
problem of the uniform rapidity of the magnetic machine ; for, being put 
in motion by the magnetizing power of a voltaic current, it represents 
simultaneously an apparatus composed of magnets in motion, and ca- 
pable of producing a magneto-electric current, in a direction contrary 
to the voltaic current. The first is closed by the pile itself, which, being 
composed of a single pair only, does not offer too great a resistance to 
its passage. 
In the connecting wire, formed by the union of the sixteen helices of 
the apparatus, I interposed a galvanometer; and then, by closing the 
circuit and preventing the motion of the machine, I observed the devia- 
tion of the needle: it amounted to nearly 60°. As soon as the motion 
of the apparatus commenced the needle began to recede, and continued 
to do so more and more as the speed became more accelerated. The 
motion having become uniform, at the rate of 60 revolutions in a mi- 
nute, the needle became stationary at a deviation of about 47°. The 
needle always advanced when the motion was stopped or retarded ; it 
receded, on the contrary, when it was mechanically accelerated. It ap- 
pears that the deviation of the needle of 47° corresponds with the state 
of equilibrium; for the motion having of itself ceased, the needle did 
not quit this position. Thus in the different experiments, whether the 
first deviation of the needle exceeded 60°, or was less, it always became 
fixed at about 47°. The voltaic current having been weakened by the 
interposition of different branches, until the first deviation amounted 
only to 47°, the magnetism was not sufficiently strong to produce the 
- movement of the apparatus. Repeated experiments will be necessary 
to investigate these interesting phenomena. 
19. 
I imagined that it would be useful to open two passages or two 
separate branches to the magneto-electric current; one of which should 
be the pile, and the other a second connecting metallic wire, so long and 
so thin as not too much to affect the quantity of electricity passing 
through the principal connecting wire. (Art. 8., No.6.) There was 
reason to suppose that the counter-current would rather follow the 
metallic wire than the liquid of the pile: but it was not so. Du- 
ring the motion of the apparatus, the needle of the galvanometer 
_ being fixed at 47°, and the second circuit having been suddenly esta- 
blished, the needle was not much affected by it. It advanced, it is 
true, but only 1°°5. Neither did the speed of the apparatus sensibly 
_ change. On reducing the length of the second wire it was nearly the 
same. The passage of the counter-current across the metallic wire 
was proved, at least in part, by the interposition of a second galvanome- 
ter. During the accelerated movement the needle of this latter ad- 
