no error, either in respect to theory or practice. In this early stage
of our system's history, it would be remarkable if it did not contain
errors in both these respects. But what it is intended to affirm is,
that the book presents the _cardinal features_ of a true, and the only
possibly true, system of electrical practice. All possibly true systems
of geometry must necessarily be essentially the same; and so, too, all
possibly true systems of electrical medication must be essentially one.
That one system, it is candidly and confidently believed, is briefly
contained in the present little volume.

ELECTRICAL MEDICATION.

FIRST PRINCIPLES.

DR. JEROME KIDDER'S ELECTRO-MAGNETIC MACHINE.

On opening the machine-box, as it comes from the manufacturer, there
will be found a glass bottle, intended to hold the battery fluid when
not in use; a glass cup or jar, to serve as the battery cell; a pair of
insulated metallic conducting cords; two tin electrodes; a brass clamp;
and, under the helix-box, (which raise), the battery metals and two
connecting wires to unite the battery with the helix.

To put the machine in working condition--ready for use--proceed, step by
step, as follows, viz: Prepare the _Battery Fluid_ by mixing twelve
parts, by measure, of water with one part of sulphuric acid, (good
commercial acid is pure enough), sufficient to fill the cell two-thirds
or three-fourths full, and place in it about one-third of an ounce of
quicksilver.

Next, place the platina plate between the two zinc plates, standing on
their legs upon a table before you; and bring the top of the wooden bar
(in a groove of which the platina is set) up flush with the top of the
zinc plates. Let the brass post, standing on the top of this bar and
soldered to the platina plate below, be toward the left-hand side. Then
take the brass clamp and place it across the top of these metallic
plates, a little to the right of the brass post, or about midway between
the right and left sides, having its thumb-screw towards you, and with
it screw the three plates firmly together. The platina is shorter than
the zincs, to prevent its reaching the quicksilver in the bottom of the
cell; and the wax balls on its sides are to insulate it from the zinc
plates. This platina should never be allowed to touch the mercury or the
zinc.

Let the plates, properly screwed together, be now placed in the cell
with the Battery Fluid. Then, with the two copp