er connecting-wires,
connect the post which stands on the wooden bar above the platina with
the post stamped P on the helix-box, and the brass clamp N with the
post N on the helix-box.

If, now, the screws regulating the vibrating armature be in perfect
adjustment, the current will commence to run, with a buzzing sound; or
it may be made to start by touching the hammer-like head of the flat
steel spring. If not, the screws may be rightly adjusted in the
following way: The top screw, which at its lower point is tipped with a
small coil of platina wire, should be made to press delicately upon the
center of the little iron plate on the upper side of the spring, so as
to bear the latter down very slightly. Then raise or depress the
screw-magnet, which turns up or down under the hammer, like the seat of
a piano-stool, until the vibration of the spring commences. The
_rapidity of the vibrations_, by which is secured the alternate closing
and breaking of the electric circuit (or rather what, in practical
effect, is equivalent to this--the _direct_ and _reverse_ action of the
current in alternation) is increased by raising the screw-magnet and
diminished by lowering it. When it is raised above what is required for
ordinary use, the noise becomes too loud and harsh for many nervous
patients to bear. It should then be depressed a little.

With respect to curative power, I have discovered but little perceptible
difference, produced by the various degrees of rapidity in the
vibrations, effected within the range of this magnet.

_The force_ of the current is regulated by means of a tubular magnet,
which slides over the helix, and is called _the plunger_. It is
approached under a brass cap at the right-hand end of the machine. The
plunger is withdrawn, more or less, to increase the force; pushed in to
diminish it. If in any case the current can not be softened sufficiently
with the plunger, the quantity of battery fluid in use must be made
less.

After a time the current will become weak, and fail to run well. Then
renew the battery fluid. When the quicksilver is all taken up by the
zinc plates, the machine may be run for a while without adding more. But
after it has considerably disappeared from the inside surface of the zinc
plates, the latter will begin to show more rapid corrosion, while the
current will be less. Then let a small quantity of quicksilver--one-fourth
to one-third of an ounce--again be placed in the fluid.

Wh