IMPROVEMENTS IN ELECTRO- MAGNETIC CLOCKS
Year: 1878

page_text: LETTERS PATENT to Charles Shepherd, of Alexandra Road, Saint John's Wood,
in the County of Middlosex, for the Invention of "IMPROVEMENTS IN ELECTRO-
MAGNETIC CLOCKS."
Sealed the 1st November 1878, and dated the 20th June 1878.
PROVISIONAL SPECIFICATION left by the said Charles Shepherd at the
Office of the Commissioners of Patents on the 20th June 1878.
CHARLES SHEPHERD, of Alexandra Road, Saint John's Wood, in the County of
Middlesex. "IMPROVEMENTS IN ELECTRO-MAGNETIC CLOCKS."
.
This Invention has for its object improvements in electro-magnetic clocks, and is
designed to prevent their stopping in the event of failure of a battery or accidental
cutting of a circuit. For this purpose in conjunction with a suitable pendulum I
arrange two or more separate and distinct circuits, each having two batteries
sending reverse currents. Each of these batteries I make sufficiently powerful to
be alone capable of keeping the clock going.
In the circuits I provide coils, in juxtaposition to which I arrange three or more
permanent magnets on a shaft operating in gear or connection with the train of
clockwork. The pendulum is in connection with each circuit. By this arrangement
the magnets will be kept revolving in perfect synchronism with the pendulum.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Shepherd in the Great Seal Patent Office on the 19th
December 1878.
CHARLES SHEPHERD, of Alexandra Road, Saint John's Wood, in the County of
Middlesex. "IMPROVEMENTS IN ELECTRO-MAGNETIC CLOCKS."
This Invention has for its object improvements in electro-magnetic clocks, and is
designed to prevent their stopping in the event of failure of a battery or of
accidental cutting of a circuit. For this purpose in conjunction with a suitable
pendulum I arrange two or more separate and distinct circuits, each having two
batteries sending reverse currents. Each of these batteries I make sufficiently
powerful to be (alone) capable of keeping the clock (or clocks) going.
•
In the circuits I provide for each clock coils, in juxtaposition to which I arrange
permanent magnets on an arbour operating in gear or connection with the train of
clockwork. The pendulum is in connection with each circuit. By this arrange-
ment the magnets will be kept revolving in perfect synchronism with the
pendulum.
In carrying out my Invention I use heavy broad bar magnets, which I so arrange
in relation to coils as to somewhat resemble an ordinary galvanometer.
If the coils of such an arrangement are made part of a circuit of a single cell of a
galvanic battery, the circuit being made and broken by a penduluin, the bar
magnet after having been once started revolving will continue to revolve
synchronously with the motion of the governing pendulum, inaking one revolution
to each double vibration of the pendulum. This will continue notwithstanding
great variations in the power of the electric current used, and even if that power
should be many times inore than is necessary to keep the magnets in motion;
hence, the coils being divided into separate circuits, each having a separate battery
and contact spring for making and breaking contact with the pendulum, as
described, each battery, acting in its own circuit, is by itself able to keep the bar
magnets revolving as already mentioned; thus, for example, if four batteries are
used, should three out of the four fail, or should their communicating wires be
damaged, the fourth battery would suffice to keep all the magnets revolving.
•
The electric current required to keep the bar magnets revolving is so small that
a large number of them may be kept going by a single cell, the coils of each clock
being a separate branch (leak) or circuit between the main wires connected with
the poles of the cell or battery.
My Invention may be applied to the driving of one, two, or other number of
clocks.
In the Drawings I have shewn it as applied to the driving of three clocks, a
separate set of coils being provided for actuating the pendulum; but where only
.one train of clockwork is required to be driven, the same set of coils and magnets
that drives the train of wheels for moving the hands over the dial inay also actuate
the pendulum, as will be herein-after explained.
Referring to the accompanying Drawings,―
Fig. 1 is a diagram shewing an arrangement of batterios and connections for
working clocks on my plan. Four batteries are here represented in two circuits,
but two batteries may be used in one circuit, or the number of circuits may be
increased if desired. Four batteries, as represented, will be found to give ample
security against accidental failure of batteries, as also against accidents to which
the wires may be exposed in a house, or even in a large establishment where many
clocks are required.
A1, A2, are the batteries of the left circuit; 1* and 2* are the main wires
connected with these batteries. The carbon C of A' and the zinc of A² are
connected with main wire No. 1*, represented by dots and lines alternating,
thus.
The wire is carried round so as to join both ends to the spot
from which it starts. The zinc of A' and carbon of A³ are connected respectively

page_text: with the contact springs 1 and 2 (see also Fig. 3). The insulated pieces of
platinum 3 and 4 attached to the pendulumn rod 5 are connected by the fine spiral
spring 6 to the binding screw 7 from which leads the main wire No. 2*, reprosented
by dots, thus... which main wire aftor making the round parallel to main
wire No. 1x returns to binding screw 7.
As the pendulum 5 swings to the left the platinum 3 will be brought into
contact with spring 1, thereby completing the circuit from Z of battery A¹ through
the spiral spring 6 to binding screw 7; the main wire 1* will now be positively
polarised and the main wire 2* negatively polarised. On the swing of the
pendulum to the right, contact will be broken between 1 and 3 and made between
2 and 4, bringing battery A* into action, this will produce an opposite state of
polarisation of the main wires; No. 1* will now be negative and No. 2* positive.
At 8, 9, and 10 are represented the coils of three clocks, such as are herein-after
described with reference to Figs. 6, 7, and 8, and at 11 are. represented the four
coils necessary to keep the pendulum in motion, as herein-after described with
reference to Figs. 2, 3, 4, and 5. The whole of the left coils are connected by
branch wires with the main wires 1× and 2×, the inner end or commencement of
each coil being connected with No. 1*, and the outer ends being connected
with No. 2*.
As the pendulum swings to the left, making No. 1* positive and No. 2* negative,
currents of electricity will pass from inain wire No. 1* to the inner ends of all
connected coils, and back by the outer ends of such coils to No. 2* main wire.
As the pendulum swings to the right currents will pass through all the coils in
the reverse direction from main wire 2* through the coils to main wire 1*.
Connecting the clocks in the way described, that is to say, as separate branches
or what I call "leaks," has this great advantage, viz., that the whole of the main
wires may be cut through at any one point of their course without stopping the
clocks; thus, for example, should the wires be cut at x, x, the coils at 8 and 9
would receive the electric currents by the portions ×¹, x¹, of the main wires, and
the coils at 10 and 11 would receive the electric currents by the portions x2, x3, of
the main wires.
The batteries B1, B2, are connected with the main wires 3* and 4* and the
contact springs 12 and 13, and as the pendulum swings act precisely as described in
reference to the left circuit, only these batteries are made to send their currents
through the right-hand coils of all the connected clocks, these currents passing
simultaneously with and acting in unison with the currents sent through the left
coils by the batteries of the left circuit.
The two circuits with their separate batteries acting only as a reserve to each
other, should the batteries of one fail or the wires be accidentally damaged, the other
is capable of doing all the necessary work, keeping the whole of the clocks in the
system going.
Figs. 2, 3, 4, and 5, illustrate the arrangement for keeping a pendulum in motion
by revolving bar magnets. 16, 17, 18, are three bar magnets; 19, 20, 21, and 22
are four coils of insulated wire. The three magnets are fixed on an arbour 23, so
as to revolve freely, the upper and lower in the slots of the coils, the middle one
between the coils. The magnets are fixed with their poles alternating, as shewn by
the letters N, S, N, so that when electric currents are sent through the coils in the
same direction, the action on all three magnets will be to turn or deflect them in
the same direction; 1, 2, and 12 and 13 are four contact springs tipped with
platinum; 3, 4, 14, and 15 are four pieces of platinum attached to but insulated
from the pendulum by pieces of ivory; the two, 3 and 4, are connected with the
insulated binding screw 7 by the fine spiral spring 6; 14 and 15 are connected
with the binding screw 24 by the fine spiral spring 25.
As the pendulum swings it alternately makes and breaks contact between the
pieces of platinum attached to the pendulum and the contact springs, which being
connected with galvanic batteries as already explained, causes electric currents to
pass through, the coils 19, 20, 21, and 22; if the magnets are now started, revolving.

page_text: in the direction indicated by the arrow in Fig. 4, they will be found to be perfectly
under the control of the pendulum, making one revolution for each double
vibration.
The arbour 23, on which the revolving magnets are fixed, carries a collet with a
pin 20 fixed in it, which as it revolves acts against an arm or rod 27, lifting it into
the position shewn by dotted lines in Fig. 2, at the same time moving an arm or
rod 28 which is fixed to the same arbour (29), and thereby causing a part 30
projecting from the said arm or rod (see Fig. 5) to pass and become held by the
looked end of a detent 31 (see Fig. 3).
As the pendulum returns to the left the pointed screw 32 acting on tho
arm 31 of the detent lifts the detent and liberates the arm or rod 28, which aided
by the gravity of a weight 34 on the arm or rod 27 (attached to the same arbour
as 28) presses against the screw 33, and in the return vibration of the pendulum to
the right follows it and gives the necessary impulse to keep the pendulum in
motion.
The pendulum having completed its swing to the right, the magnets will have
made an entire revolution and the pin 26 will again come in contact with the
lever 27, and lifting it will onco more lock or engage the projection 30 of the
impulse arm or rod 28 in the detent 31, in readiness to be released for giving
another impulse to the pendulum 5.
The collet carrying the pin 26 is fixed on the arbour 23 by a screw, so that it
can be moved and adjusted to move the impulse arm or rod 27 at the desired
moment when the pendulum completes its swing to the right.
Figs. 6, 7, and 8 shew the method of applying the rotary magnets to driving
sympathetic clocks. These, when of ordinary size, say, up to dials 2 feet in
diameter, will not requiro so much power as a pendulum to keep them going; two
coils, as represented in these Drawings, will be found sufficient; but for larger dials
with the hands exposed to the wind eight or more coils of larger size might be
required, the size of coil weight of the magnets and thickness of wire all being
increased; in proportion, to double the dimensions, so as to give the required power.
36 and 37 are two coils of wire; 38 and 39 are bar magnets; 40 is the arbour
carrying the magnets, so that they may revolve freely, one in the slot of the coils
and the other above the coils. The magnets are fixed with their poles in opposite
directions, as represented by the letters N.S.N.S.
I may here remark that in practice I have found it desirable that the coils I have
shewn should each contain about 1500 yards of No. 35 wire. Birmingham wire
gauge should be made of the thinnest brass consistent with the necessary strength;
also that the slots through which the magnets revolve should be made as narrow as
possible, as the closer the coils of wire are to the magnets the greater is the power
that will be obtained from a given quantity of electricity.
I have also found it desirable to inake the magnets (for the clocks shewn) about
4 inches long, 14 inches wide, and 16 th of an inch thick, and of a weight of about
500 grains. I start the magnets revolving by hand.
The arbour 40 carries at its upper end a collet with a pin 41 fixed in it, which
is so adjusted as to take into the teeth of the escape wheel 42, having thirty teeth
moving it forward, one tooth or two seconds for each revolution of the magnets;
the arbour 43 of the escape wheel is held by two springs 44, 45, which are made
to press with such force as to prevent the wheel from moving except when acted
upon by the pin 41.
The train of clockwork represented as being thus driven is an ordinary arrange-
ment minus springs or weights.
'
It will be evident other arrangements of clockwork may be actuated on my plan,
and that instead of the escape wheel with thirty teeth, a wheel of sixty teeth may
be used in conjunction with two pins in the collet so as to cause the hand to
indicate seconds.
Other methods than that I have shewn may be employed to communicate notion
from the arbour carrying the magnets to the train of clockwork employed. For

page_text: instance, the arbour may carry a pinion in gear with a toothed wheel on the
arbour 43 or its equivalent.
I would also remark that if a pinion be fixed (in place of the collet) on the top of
the arbour 40, and taking into an ordinary toothed wheel having the proper
number of teeth, a continuous rotary motion inay be produced for driving telescopes,
et cætera.
Should it be desired in any case, the train of wheels or clockwork operating the
hands in a clock might be driven from the arbour carrying the revolving magnets
whereby the pendulum is actuated.
The arrangement of magnets and coils shewn in Figs. 2, 3, 4, and 5, would be
found of ample power for these two purposes. I do not however recommend the
use of the same magnets for the two purposes.
Having thus described the nature of my Invention, and the manner of carrying it
into practical effect, I would have it understood that what I consider to be novel
and original, and therefore claim as my Invention is,—
1. The method of combining or arranging in connection with a clock pendulum,
two or more separate and distinct circuits, each having two batteries sonding
reverse currents, substantially as described for the purpose specified.
2. Driving clocks by the rotary motion of magnets produced by the use of coils in
electric circuits controlled by a pendulum, substantially as described.
3. The method of arranging the coils in connection with the main wires of the
batteries, substantially as herein-before described with reference to Fig. 1 of the
Drawings, so that the branch wires to the coils constitute leaks whereby the
requisite currents are caused to pass through the coils even when the main wires are
cut or divided at any one place.
4. The constructing electro-magnetic clocks, as herein-before described, and shewn
in the accompanying Drawings.
In witness whereof, I, the said Charles Shepherd, have hereunto set my hand
and seal, this Eighteenth day of December, in the year of our Lord One
thousand eight hundred and seventy-eight.

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