Specification forming part of Letters Patent No. 7,420, dated June 4, 185O.

To all whom it may concern:

Be it known that I, SAMUEL B. SMITH, of
the city of New York, in the county and State
of New York, have invented a new and useful
Machine for Medical Purposes, for Electro.-
Magnetic Plating, and for other Chemical Pur-
poses.  The machine is all electromagnetic
machine.  To distingnish it from the ordinary
electromagnetic machines, and to designate
its action I call it the "Automatic Direct and
To-and-fro Current Electro-Magnetic Ma-
chine;" and I do hereby declare that the fol-
lowing is a full, clear, and exact description
of the construction and operation of the same,
reference being had to the annexed drawings,
making a part of this speciflcation, of which-
     Figure 1 is a perspective view.
Letter A is the-helix or coil of flne and coarser
wire of copper; B B, the electromagnet; C,
the armature, which revolves with,its vertical
axis on two jewels; D, a screw for adjusting
the armature; E, a brass post, to which the
springs are screwed; F, a spring, which is in
electric communication with one end of the
fine and of the coarser wires of the helix-in
connection with the coarse wire after having
formed the helix and been coiled around the
electromagnet, and thus conveying the pri-
mary current to the break-piece on the axle of
the armature; G a spring which is in com-
munication,through the post E, with the other
end of the fine wire.  Near the ends of the
three Springs F, G, and H is soldered onto the
springs a small strip of silrer, which alter-
nately-strikes the break-piece as it revolves.
H. a spring, which is in contact with the coarse
wire which leads direct to the battery; I, the
break-piece; K, a stay, at one end of which
is fixed a strip of gutta-percha, to keep the
springs F and G from approachong too near the
break-piece: L a mobable wire to be used
when required to press the spring G off from
the break-piece: M M, two screws, insulated
at one end of them to press against the springs
F and G to regulate their pressure against the
Break-Piece; N, a brass post, into a hole near
the upper end of which is placed a conducto-
ing wire from the zinc of the battery; O, an
other brass post, for receiving a conducting-
wire from the copper of the battery; P, a brass
post for receiving the conducting wire of the 
secondary current; Q, another brass post for
receiving the conducting wire of the secondary
current-the one negative, the other positive.
     Explanation of the manner in which the ma-
chine operates and further explanations rela-
tive to particular parts:  Any of the ordinary
galvanic batteries will answer for this machine.
The connections for the passage of the elec-
tricity are made as follows: A connecting-wire
leads from the copper of the battery to the
post 0. From this post it passes on, at the
bottom of the stand on which the helix is
placed, to the helix.  Having formed two lay-
ers of the. coil of the helix, it passes on to the
magnet B, around which it makes two layers.
It then passes on over the bottom of the stand
and terminates on the spring F. Another con-
nectiog-wire leads from the zinc of the battery
to the-post N. It then passes over the bottom
of the stand and terminates on the spring H.
In this way the entire galvanic circuit of the,
primary current is formed.  The fine wire, (of,
which there are from twelve to sixteen layers
wound over the two,layers of the coarse wire,)
after passing around and forming the helix,
runs as follows: One end of it is soldered-onto
the coarse wire of the primary coil on the bot-
tom of the stand.  It is soldered onto the part
that leads to the magnet B. The other end of
the fine wire passes through, also, to the hot-
tom of the stand, and it is soldered to the post
P. It then passes on, terminates at, and is
soldered onto the bottom of the post B. From
this juncture, the post being brass, there is a
metallic communication to the spring G, but
no such communication to the springs F and
H, which are insulated from it by gutta-percha
washers.  There is a washer of gutta-percha
between each of these two springs and the post,
and between the springs and the heads of the
screws which hold the springs to the Post,
the holes in the springs through which the
screws pass being sufficiently large to prevent
a contact between the screws and the springs.
When the machine is in operation, and at the
moment when the, break-piece I strikes the
silver strip on the spring F, there is no com-
munication between the break-piece and silver
strip on the spring G, but there is a commu-
nication between the silver strip on spring H
and the break-piece.  Coniequently at this
juncture the circuit of the primary current is
closed.  At this instant of contact between the
positive and negative electric states the shock
is transmitted and felt at the terminations of
the fine wire, or at any points in metallic com-
munication with those terminations.  In other
words, it is felt at the posts P and Q, which
are in communication with the terminations of
the fine wire.  As the armature revolves the
break-piece ceases to be in contact with the
silver strip on spring F. Just previous to this
break of contact, the break-piece comes into
contact with the silver strip on spring G, the
contact on silver strip on spring H still con-
tinuing.  Under tbew circumstances when the
contact, at spring F is broken the shock is not
transmitted nor felt at either of the posts P or
Q, because the electric current of the secondary
or fine wire passes through the battery.  The
armature still revolving, the break-piece again
strikes the silver strip at spring F, aud the
same results follow as have been described.
In this manner no electric current is transmit-
ted to the posts P and Q, but the direct cur-
rent, the back current, or the to-and-fro cur-
rent of the ordinary electromagnetic machines
being thus wholely avoided.
     The following experiments demonstrate the
accuracy of the above statements: Pour into
a glass tumbler a metallic solution-the sul-
phate of copper, for instance. (Care abould be
taken that the solution be made of rainwater.)
Introduce into this solution a piece of platina
plate soldered onto the end of a metallic con-
ductor leading to post P. - In like manner in.
troduce another piece,of wire into the solution
with a piece of platina soldered to the end of
it and connect this with the post Q.  Let the
two pieces of platina be a short distance apart
in the solution.  Put the machine into opera-
tion, and immediately the process of electro-
plating commences, and in a few minutes the
platina on the negative conductor will be found
to be well coated with copper, while none of
the copper will be on the platina at the end of
the positive conductor.  Reverse the poles-
that is, place the coarse connecting-wire that
was in connection with the copper of the bat-
tery into connectin with the zinc, and that
which was in connectiou with the zinc into con-
nection with the copper-and the copper precip.
itate which was deposited on the former nega-
tive conductor will be driven from it, and the
platine on the end of the other wire, which is
now made negative, will be found to receive a
metallic coating.  The deposition of metals on
the negative conductor of the voltaic battery
is a well-known fact. No such effect ever takes
place on the positive conductor, from whence
the electric current flows.
       We will now try another experiment illustra-
tive of the effect of the to-and-fro direction of
the electric current in the ordinary electro-
magnetic machines.
    In the annexed drawing, L is a brass wire,
movable on a journal at the top of the post
which supports it.  By moving this wire around
till the end of it presses against the wpring G
said spring is borne off till the slter strip on
it is no longer in contact with the break-piece
Under this circumstance this machine is made
to act on the to-and-fro principle, the same as
the ordinary electro-magnetic machines.
It acts now on this principle, because the electric
current of the secondary or fine wire does not
now pass through the battery, but pases to and
fro in a direction in which the posts Q and P
are in the circuit. With the machine in this
situation we will again introduce the two wires
into the tumbler in the same manner as in the
former experiment. The machine is now put 
into operation, but instead of finding the pla-
tina on the negative conductor to become coated
with copper, we find no such coating-no more
than at the positive conductor.  We may con-
tinue the operation any length of time and no
metallic deposti takes place.  Again, let us
remove this wire L from the spring , and the
metallic coating immediately commences on
the negative conductor as in the experiment
at first.
    There is a great advantage in the above-de-
scribed machine, in that the direct current can
be used, when it is requisite, without the to-
and-fro current.
    As a therapeutic agent, there are many dis-
eases in which the to-and-fro current is indi-
cated and is beneficial.  There are other dis-
eases in which it is injurious.  The to-and-fro
current is useful when an alternative and stim-
ulant are wanting.  In such cases it is a valu-
able medical agent.
    What I claim, threfore, as my invention, and
desire to secure by Letters Patent, is-
    1. Separating the shock derived from the
initial secondary current of the double-coil
magneto-electric machine from that of the ter-
minal secondary by causing the latter to pass 
through a closed circuit, substantially in the
manner and for the purposes set forth.
    2.  The manner of adapting the same machine
to transmit both the initial and terminal sec-
ondary currents at pleasure by bearing off the
spring G by the arm L, substantially as de-


Hohn B. Gardner
N. H. Gale


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