By removing the coil, A, from beneath the compass, E, and connecting
the ends of the transverse wire, a' a', with the battery Fig. 16, then
lifting the plates of the battery out of the solution and allowing the
needle to come to rest, it will be found upon inserting the plates of
the battery in the solution, very gradually, that the deflection of
the needle will increase with the increase of plate surface submitted
to the action of the battery fluid; and if, when the greatest
deflection is reached, the coils or solenoids are introduced into the
circuit, one after the other, it, will be found that each added coil
diminishes the current, as will be shown by the diminished deflection
of the needle.
[Illustration: FIG. 16.--EXPERIMENT SHOWING THE CURRENT.]