IMPROVEMENTS IN ELECTRO-MAGNETIC CLOCKS
Year: 1872

page_text: LETTERS PATENT to Benjamin Joseph Barnard Mills, of the Firm of
Harris and Mills, of 35, Southampton Buildings, in the County of
Middlesex, Patent Agents, for the Invention of “IMPROVEMENTS IN
ELECTRO-MAGNETIC CLOCKS."-A communication from abroad by William
Monroe Davis, of Cincinnati, Hamilton County, Ohio, United States
of America.
Sealed the 29th November 1872, and dated the 9th October 1872.
COMPLETE SPECIFICATION filed by the said Benjamin Joseph Barnard
Mills at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 9th October 1872, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
JOSEPH BARNARD MILLS, of the Firm of Harris & Mills, of 35, South-
ampton Buildings, in the County of Middlesex, Patent Agents, send
greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN ELECTRO-MAGNETIC CLOCKS." and have petitioned Her Majesty to grant

page_text: unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that the same
is a communication to me from abroad by William Monroc Davis, of
Cincinnati, Hamilton County, Ohio, United States of America.
NOW KNOW YE, that I, the said Benjamin Joseph Barnard Mills,
do hereby declare that the following Complete Specification, under my
hand and seal, fully describes and ascertains the nature of the said
Invention, and in what manner the same is to be performed in and
by the following statement thereof, that is to say :—
The present Invention relates to improvements in that class of
electrical clocks whose impulsion is wholly due to the electro-magnetic
force which regulates them, and in which a primary or regulating
pendulum is made to communicate its motions isochronously to one or
more clock movements, whether near or distant.
There are timekeepers now in use miscalled electrical clocks, which
are merely clocks of customary construction kept in motion by a wound-
up weight or spring, and are termed "electrical clocks," cither because
their errors are corrected at shorter or longer intervals by electrical
impulses from a prime regulator, or because they themselves perform
this function of prime regulator.
In this class of clocks the electrical impulses are employed not to
propel but for correction only, at stated intervals of the slow or fast
time of the secondary clocks or their primaries.
The failure of these clocks to come into general use is attributable in
part to the large original cost of their construction and the attention
required to keep them running, and in part to a still more serious
difficulty, namely, the deterioration of electrical contact in the rheotome,
to which they in common with electrical clocks proper are subject;
this deterioration it is one object of this Invention to obviate. This
deterioration seems to be caused by the deposit of an exceedingly thin
non-conducting film on the contact surface of the rheotome by the
continued action of the spark which is generated there at each interrup-
tion of the clectric flow. The Inventor sensibly reduces the spark, and
so far as appears entirely avoids its deleterious consequences by im-
mersing the contact points in a liquid solvent or medium, such as
kerosene or other suitable liquid, which whether preventing the forma-

page_text: tion of the film or removing it as fast as formed, has proved efficient as
a means of preserving the electrical integrity of the contact surfaces.
The Inventor has found fish oil and some other oils and even water to
discharge more or less perfectly the described functions of kerosene.
As an additional safeguard of this vital necessity of continual electrical
impact, the Inventor has contrived and adopted what may be called a
sparkless current shifter or current switch. This shifter is so constructed
as to change the route of the electric current from one closed circuit to
another without at any time breaking the continuity of its flow. By
this last-named expedient the above deleterious consequences are obviated
through the entire suppression of any sensible spark.
Electrical clocks proper are further liable to a failure of their rheo-
tomes to perform their functions properly, even while their contact
surfaces remain intact. This improper performance of the rheotome
may be either one of the two opposite kinds, namely, it may fail occa-
sionally to make electrical contact, or it may, by a kind of rebound,
make a double contact by a single impulse of the primary. In the first
case, the secondary clock would fail to receive the required impulse, and
consequently would fall behind the time of the primary, while in the
second case the secondary clock would receive a false or double beat,
and would consequently move forward in advance of the time of its
primary. Defective performance of the secondaries occasionally arises
from the action of atmospheric electricity.
When the conducting wires of electro-magnetic clocks proper are
exposed to the open air those disturbances known as " electrical
storms"
are apt to derange the motions of such secondary clocks,
usually by moving them forward in advance of the time of their
primaries.
Thus three distinct sources of error intervene to injure the usefulness
of electro-magnetic clocks proper.
A remedy for one of these (defective impact from long use) has already
been explained, and those for the others will now be briefly set forth.
To obviate these two sources of error the Inventor interposes between
the electro-magnetic helix and the train of wheels which move the
hands of the secondary clock a secondary "pulsator."

page_text: The word "pulsator" is here adopted as a term, including all those
various forms of vibrating, oscillating, or gyrating masses which are used
to regulate the motions of timekeepers.
The secondary "pulsator" in all its forms should be so adjusted that
its normal beats shall be sensibly isochronous with those of its primary,
and must have sufficient vis inertia to bridge over or neutralize the
occasional failures and false performances of the rheotome by compelling
a uniformity of beat in the secondary. This secondary pulsator owes
its original and continued motion wholly to the electro-magnetic im-
pulses transmitted from the primary, and its vis inertia when it is once
in full swing is sufficient to rectify any momentary aberration of these
electrical impulses.
The Inventor thus secures for electrical clocks proper the advantages
of special pulsators in their secondaries, advantages hitherto confined to
clocks driven by weights or springs only, and yet avoids the expense and
uncertainty attending the employment of such weights or springs.
And in order that the said Invention may be more clearly understood
and readily carried into effect, I will proceed aided by the accompany-
ing Drawings more fully to describe the same.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a view of the preferred form of primary and secondary
pendulums and their accessories, including one form of the sparkless
shifter with air-tight case for the same; Figure 2 is a view of this
shifter with the air-tight case removed; Figure 3 is an axial section of
the same with the air-tight case in position; Figure 4 represents the
lower end of the vertical shaft R of this shifter on a larger scale;
Figure 5 is a front elevation of a primary pendulum with the compound
sparkless shifter, Figure 5 also includes a secondary pendulum with
combined feed hand and detent; Figure 6 is an enlarged view of the
combined feed hand and detent in a different position from that in
Figure 5; Figure 7 is a view of the detent plate detached; Figure 8 is
a plan view of a horizontal pulsator called by me a "vibrator" and
certain adjuncts thereto. This vibrator is constructed like a common
pendulum, but caused to vibrate in a horizontal plane. Figure 9 is an
inverted view of the cut off rheotome of Figure 8; Figure 10 is a
view of a gyrating pendulum performing the function of a secondary

page_text: "pulsator," showing the Inventor's mode of equalizing the force used
to move such pendulum, Figure 1 is a sectional view of a sparkless
shifter of another form without its air-tight case; Figure 12 is a cross
section of the same with the air-tight case in position; Figure 13 is
an elevation of another form of the compound sparkless shifter in
connection with detached lubricating cuns in section.
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shifter of another form without its air-tight case; Figure 12 is a cross
section of the same with the air-tight case in position; Figure 13 is
an elevation of another form of the compound sparkless shifter in
connection with detached lubricating cups in section.
DESCRIPTION OF PRIMARY AND SECONDARY PENDULUMS AND THEIR
ACCESSORIES. (Figures 1, 2, 3, and 4.)
A is the stand or frame to which the operative parts of the preferred
form of primary pendulum are attached; B is the pendulum "bob,"
and 6 its rod; C is the bracket which supports the gimbal bar D, which
clamps the upper ends of the suspending springs of the pendulum; E is
a divided bar to clamp the lower ends of springs e, e', and the upper end
of the rod b. Projecting from opposite sides of the upper end of the rod b,
and in its plane of vibration, are the two impelling arms F, F¹; G is an
electro-magnet whose armature H is attached to the rock shaft I, which
shaft is journaled horizontally in bearing C₁, C¹. On the opposite side
of the shaft I is the retracting spring g, opposed to magnet G, and
designed to actuate the shaft I in the opposite direction. Projecting
from opposite sides of shaft I are the lifting levers J, J', having the
represented or other suitable bent or hooked extremities to hold the
impelling weights K, K'. L represents one form of the sparkless shifter
enclosed in an air-tight case; 1, F, are its impulse horns; a is the
bracket to support the shifter (L); N, N', are conducting wires which
lead from the shifter through the two magnets G and G', to one pole
of a galvanic battery P; O is a conductor which connects the
shifter L directly with the other pole of battery P. Firmly secured
upon base a is a cup Q to hold mercury S. A step on the bottom of
said cup (see Figure 3) receives the lower end of the vertical rock
shaft R, whose upper end is supported by a suitable frame Q' and screw
socket q. To the rock shaft R, just above the mercury S, is attached
the switch T. The lower surface of the outer end of the switch T
has a convex protuberance of hard metal, usually iridosmiam, which
constitutes the contact point of the switch T. U, U', are the insulated
contact points and terminii of the insulated wires N, N'. The wire O
is put in electrical connection with mercury S. by a platinum plate,
not shown in the Drawing. V is an insoluble insulating air-tight

page_text: cement, which fills the bottom of the case L nearly to the tops of the
points U, U', surrounding without entering the cup Q, and effectually
closing the bottom of the case. Above this cement and submerging the
contact points U and U', the switch T, and the mercury S, is the liquid
medium above specified, and which is designed to preserve the integrity
of the contact points of the shifter. The upper surface of this liquid is
represented by the dotted line W. This liquid may be kerosene or any
other suitable liquid as already explained. X is an air-tight cover in
the form of an inverted cup, whose lower edge occupies the hermetical
trough Y, which surrounds the case L near its top, and contains
glycerine or other suitable liquid to hermetically close the case L.
Projecting from the cover is a flange X', which resting on the outer
edge of the trough Y upholds the cover's lower edge from the bottom of
the trough.
The vertical shaft R is of steel wire about (one-twentieth
of an inch in diameter and about three inches long, and has conical
bearing points. The lever L' and the horns 1, l, are made of watch
spring blade weighing about 24 (two and a half) grains to the inch. The
switch T is a thin spring of silver about, (five-eighths of an) inch long.
That portion of the shaft below the switch T is encased in platinum r.
The mercury in the cup Q is about (half) an inch deep and is designed
to secure free electrical connection between the wire O and the switch T.
The liquid medium above it is about 1 (one and a quarter) inches
deep. The pressure of T on the points U and U' is just sufficient to
maintain electrical contact during its passage from one of these points
to the other. The distance between the two points U and U' is barely
sufficient to insulate the one from the other, in this case about roσ (one
hundredth of one) inch. The hard point t is of such size that it does
not leave one of the points U or U' until it has fairly come in contact
with the other, thus preserving at least one unbroken or continuous
circuit for the electric current, by this means the electric spark is avoided.
The space required for the point T to traverse in order to change the
current's course from one route to the other is less than 1 (onc-sixteenth
of one) inch, but more motion than that is usually given to it, in order
to prevent abnormal action of the shifter arising from any slight
variation in the vertical position of the clock case. The lever L' is
double kneed, so as to pass down through the liquid contained in the
trough Y, in order, to allow the lower edge of cover X to enter this
liquid, so as to exclude the external air without interfering with the
free motion of said lever.

page_text: A is the stand to which the operative parts of the secondary pendu-
lum and secondary clock works are attached. The secondary pendulum
is formed of parts B', b', E', e³, e³, C², similar to those which compose
the primary pendulum; D' is a bracket which supports the secondary
magnet G F is the impulse arm secured to El at right angles to the
rod. The armature H' of magnet G is firmly secured to the lifting
lever J, which lever is secured to the frame A' by the bracket I';. K' is
an impelling spring securely attached to the lever J, having a link
formed at its lower end to receive the arm F2; M is a check bar
supported by brackets a¹, a²; o, o', are two tappet pins to the bar M;
Z, Z', are pallets secured to the pendulum rod for the purpose of impelling
the pin scape wheel Q. These pallets are made quite long, as here
represented, in order to allow the pendulum its necessary amplitude of
swing, and at the same time to serve as detents to the wheel Q. It
may here be observed that these pallets operate to drive the scape wheel
instead of being driven by it, as in ordinary clockwork; m is a catch
pawl to prevent a retrograde motion of the wheel Q³.
OPERATION OF PRIMARY PENDULUM AND ITS ADJUNCTS.--(Figure 1.)
The pendulum B, b, being put in motion by the person in charge,
the rod b striking against the horn of the shifter swings the switch T
on to the point U', and thus directs the current of electricity through
the distant magnet G', while it allows the spring g to actuate the rock
shaft I, and thus deposit the impeller K on the arm F, adding motion
to B in its rightward swing. As the pendulum nears the limit of its
swing to the right the rod b strikes the horn and swings the switch T
(see Figure 2) from the contact point U' to the point U, thus changing
the course of the current from wire N¹ to wire N, thereby charging
magnet G; G being charged draws the armature H promptly to its
poles, thereby lifting the impeller K from the arm F at the same moment
that it drops impeller K' on arm F. The pendulum being at the right
extremity of its swing when this action of the impelling apparatus takes
place, it is impelled again to the left, when the same operations will
be repeated.
In order to obviate any injurious effect on the time keeping qualities
of this pendulum, from the presence of the temporary magnet G, the
madh and all the moving parts attached to it including the weights W

page_text: and K', should be made of non-magnetic material. The secondary
pendulum B', ', is represented as at the left extremity of its beat;
the magnet G' being now charged in consequence of the action of
shifter L draws armature H' firmly to its poles. The lever J being
raised by this action of armature H brings into play the elastic force
of spring K, causing it to pull at the arm F, and thus impel pen-
dulum B', ', to the right. In the rightward swing of the pendulum
the pallet Z catches a pin of wheel Q, and moves it forward just as
pallet releases the opposite pin. As this motion of Q is completed
the catch pawl m falls into the next tooth on the edge of Q, and
prevents a retrograde motion of the wheel. As the pendulum nears
the right extremity of its swing the rod 6' strikes the tappet pin o', and
communicates a slight impulse to the check bar M, the object of which
will be herein-after explained. The spring K having expended its
clastic force in lifting the arm F to its highest point, and the magnet G'
being discharged at the same time by the action of primary pen-
dulum B, b, on the shifter L, the lever J' drops of its own weight, so
that impelling arm F (being at its highest point) occupies the upper
part of the link on the lower end of K². The pendulum B', ', now
takes up its leftward swing, and in doing this it withdraws pallet Z
from scape wheel Q, at the same time that it carries pallet Z' between
two pins on the opposite side of the wheel; in doing this pallet Z' moves
the pin below it downward, thus urging wheel Q: forward, so as to
cause catch pawl m to fall into the next following notch on the edge
of said wheel; while this last described operation is going on the arm F
by the leftward swing of pendulum B', 6', is descending to the bottom
of the link on K, to be in readiness to receive another impulse. The
motions of wheel Qare communicated to the hands of a clock by the
ordinary train of wheels. The construction and duty of the spring K*
and the object of the check bar M will now be described:-The spring K
must be so constructed that the amount of moving force which it can
impart to arm F° (during each charge of the magnet) and thence to
the pendulum shall be constant, and of the proper amount, in order
to give to the pendulum B', 6', a uniform and sufficient amplitude of
swing when meeting with a predetermined uniform resistance. A
gravity impeller may be used instead of a spring impeller when desirable,
but for short pendulums and quick motion the spring impeller seems
to work better. The object of introducing the check bar M will be now
explained. In order that the resistance offered to the motion of the

page_text: secondary pendulum may be as uniform as practicable, I place the
small check bar M in the path of the pendulum or its rod, and then so
adjust the impelling spring K that it shall drive the clock movement
while yet new and freshly oiled, and have a small surplus force to be
expended in giving motion to the bar M. If at any subsequent time
the clock train, from want of oil or from other cause, should require
more force to drive it than it did while new, then either the whole or a
part of the force originally appropriated to moving the bar M will be
absorbed in moving the clock train. The principal object of the check
bar M is to provide for this varying demand on the power of the pendulum
to move the clock train without changing the amplitude of its swing.
In order to secure a store of force against the emergency of an
imperfect operation of the shifter or rheotome (according to which may
be used) the tappet pins on the bar M should be so adjusted as to allow
the pendulum B', ', nearly or quite double the amplitude of swing
required to move the wheel Q2 forward one notch at each swing; by
this means a sufficient amount of force will be stored in the momentum
of the pendulum to enable it to impel the clock for some time after
the electric pulsations have ceased to reach its magnet, and to continue
to perform its proper functions indefinitely if these impulses be not
too long delayed or too frequently omitted. By its own momentum
then this secondary pendulum, or any other suitable "pulsator," when
properly combined with a secondary clock, is enabled to overcome the
evil effects arising from atmospheric electricity or from any temporary
irregularity in the performance of the rheotome. The primary pendulum
here represented may be used as a secondary, and the secondary as a
primary, by transposing the places of the shifter and the clock moving
apparatus.
Figure 5 represents by fromt elevation a primary electro-magnetic
pendulum of known construction and a modified form of secondary
pendulum, together with certain new and useful adjuncts to such
pendulums.
The
As is the frame to which the operative parts are attached.
primary pendulum is composed of the parts B2, 63, C³, et, and E³, similar
to those which compose the secondary pendulum of Figure 1. 0%, o³, are
two tappet pins firmly secured to the rod b².
The simple sparkless shifter in which liquid contact points, as mercury,
are used consists essentially of three contact points T³, T', and T³, with

page_text: wires and their corresponding switch-off points T and T convert this
simple shifter into a compound one.
This being premised I will proceed to describe the shifter in its
compound form.
L is the metallic crossed lever of the compound sparkless shifter, from
which project the five platinum contact points T, T, T", T, and T.
1, 2, 3, 4, and 5 are insulated cups containing mercury, into which these
five points are designed to dip by the operation of the rod
.
on the
lever L; is the insulating bracket to support these five mercury
cups; may represent any suitable galvanic battery; O' is a con-
ducting wire which connects battery P' with central cup 3; G² is an
electro-magnetic helix, and H' its armature secured to the lower end of
rod 6. The wires marked N³, N', and the wire N³ with its branches n
and a' lead from cups 5, 4, and 2 and 1 to one pole of the battery, while
O'leads from central cup 3 to the other pole of the battery. G³ is
another magnetic helix precisely like G, but secured to base A* on
the opposite side of the pendulum, from which pendulum projects an
armature opposite to H*.
G' remains inactive and (with its armature) may be omitted altogether
when the primary pendulum is used to drive and to regulate secondary
clocks, as it is shown to do in the Drawing. When, however, this pendulum
is used exclusively to actuate a clock movement of its own then it is
desirable that the second helix (G³) should be rendered active in order
to economize battery power. This may be done by connecting wire n
(issuing from mercury 2) with magnet G³ in the same manner as wire N*
is connected with magnet G³, being careful to connect G³ with the same
pole of the battery that G³ is now connected with; and, further, the
wire (issuing from mercury 1) must be connected directly with the
same pole of the battery without passing through the magnet, so that it
may perform the same switch-off function (soon to be described) for
magnet G³ that wire N³ does for magnet G³. As is the board to which
the secondary pendulum and its adjuncts are attached. This pendulum
is formed of the parts B³, b³, C', e³, and E³, similar to those which com-
pose the primary pendulum. G' is the magnet secured by a suitable
bracket to the board A³ with the poles directed to the armature II' (seen

page_text: and responds to its attractive power. In the rightward swing of the
pendulum the tappet o' strikes the upper end of the lever L' and presses
point T into mercury 2 before point T is withdrawn from mercury 4.
In this position of L³ the electric circuit is closed through two wires and
two magnets, viz., through G by wire N', and through distant magnet G'
by wire n, N. As the pendulum moves still to the right point T is
withdrawn from the mercury 4, thus breaking the circuit through
magnet G, but leaving it still closed through magnet G'.
If the
magnetic attraction of G during the previous rightward swing of
pendulum B, &, has been sufficient to force point T* into mercury 1
on its present return the effect on magnet G' will not be changed
thereby, because the wires and "' combine to force wire N³ which
leads through magnet G to the battery, and it makes no sensible
difference whether the current flows along one or both of these wires "
and ; in either case the magnet G is fully charged.
The object of giving the secondary magnet the full charge of the
battery at each evolution of the primary pendulum will appear when the
operation of that pendulum is explained. As magnet G is discharged
then magnet G' is fully charged, the primary pendulum B3, 6, is free
to swing to the left again. As it nears the point which it is represented
as occupying in the Drawing, the contact point T enters mercury 1
just before point T leaves mercury 2, thus closing the circuit through
magnet G before breaking it through magnet G*. When point T
leaves mercury 2 magnet G is fully charged again and will retain that
full charge during the next rightward swing of the pendulum B², ¿ª,
unless the impulse given to this pendulum during the previous charge
of magnet G was sufficient to cause it to force point T into mercury 5.
If such should be the case the switch-off character of this point T' will
be brought into play, because mercury 5 being connected with the
battery P by a short conductor N³ offering little resistance to the
electric flow, the major part of the current will be switched off through
this "short cut," leaving G³ without any sensible charge during the
next rightward swing of the pendulum. It will be found in practice
that by this arrangement and combination of the several parts just
described the limit of the pendulum's swing will be where its action
presses points T and T just on to the surface of the mercury contained
in their respective cups 5 and 1. By this automatic “switch-off”
function of these additional points T and T with their adjuncts, the

page_text: injurious consequences of any excess of battery power over and above
that required to give to the pendulum its normal amplitude of swing is
effectually obviated at each evolution of the pendulum, and as a suffi-
ciency of battery power is always required a constant excess cannot well
be avoided, hence the utility of this "switch-off" arrangement.
The
secondary pendulum B³, 13, is shown at the left extremity of its swing,
at which moment the primary will have discharged magnet G'. The
pendulum will now swing to the right, and in its course bring the
armature H against the check screw J³ just as it reaches the right
extremity of its beat. At this moment the primary pendulum closes
the circuit and recharges the magnet G. The pendulum now com-
mences its leftward swing, and at the same moment the armature H' is
drawn promptly to the poles of magnet G' in consequence of the clec-
trical charge it now receives from the primary. This leftward motion
of H* gives to the pendulum an impulse to the left in addition to that
which gravity alone would give it. If the beats of this secondary
pendulum have been properly adjusted to those of its primary, then
this continued series of isochronous impulses thus given to the secondary
will cause it to beat in unison with the primary.
I will now explain the operation of the feed hand and detent on the
time wheel W. As the pendulum B³, ³, swings to the right the feed
hand Z glides easily over the uppermost tooth of Wand falls down
behind it ready to take it up and carry it forward by the return swing
of the pendulum. A retrograde notion of W₁ is prevented at this
moment by the action of the catch pawl m³, while a forward motion is
prevented at the same time also by the interposition of the lower surface
of detent S'. As the pendulum resumes its leftward swing the feed
hand Z catches the point of said tooth, presses it up through the slot. s
in front of it in its forward motion, till finally the tooth is withdrawn
below the lower surface of the detent S¹ by the onward swing of the
pendulum, at which time the catch pawl m' takes hold of a succeeding
tooth of W to prevent its retrograde motion. Thus by each complete
evolution of the secondary pendulum the wheel W' is advanced one
tooth, and thus the beats of a primary pendulum may be faithfully
indicated in a distant dial. This primary may be easily converted
into a secondary by substituting a clock movement for the shifter and
charging its magnet by a suitable primary.

page_text: These parts are differently pro-
order to fit the vibrator for its
are much stronger than in the
much lighter. The vibrator and
G³ is the electro-magnet secured
This "vibrator" is composed of the parts B', b', C³, E', e, similar to
pendulums herein-before described.
portioned to each other, however, in
different position; thus the springs
pendulum proper, while the bob B' is
its adjuncts are secured to the base A';
to base A*; H³ is its armature attached to the free end of rod b.
The rheotome is a thin plain bar of rigid non-conducting material into
which is interwoven the conducting wire W' in such a manner as to
form the contact points T and T on the lower side of the bar, and to
form also the connecting wire between them as seen on the upper side
(in Figure 8). U and U³ are metallic brackets used to support the
bar L' and also to form contact points for tho wires N' and O which
are attached to them. No is a conducting wire which leads from the
rheotome or bracket U' through the magnet to one pole of the
battery P; O' is another conducting wire connecting rheotome L³
through bracket U³ directly with the other pole of the battery. The
contact surface T is formed of two longitudinal portions of this con-
tinuous wire lying along the lower surface of the bar near one end and
very near its edges, this last in order to prevent the bar from tilting
while in motion. The length given to these two portions of the wire
is designed to secure constant contact between the wire and its sup-
porter Us, in whatever position the rod b' may place the bar.
The
point T is formed of a very short portion of this same wire, which is
passed through the bar at a distance from the centre of T equal to
the distance between Us and U³. This rheotome is placed as near
to the lower side of rod b' as is consistent with the free motion of the
latter. Two tappet pins o' and o" projecting upward from this bar
arc struck alternately by the rod causing a reciprocating motion
of the bar.

page_text: this position) moved the rheotome L³ so as to bring the point T on
to the contact point U³, thus closing the electric circuit and charging
magnet G³, the position of pin o' on bar L' having been so adjusted
as to produce this effect. The vibrator is now urged toward the
magnet G by the elastic force of its supporting springs, and as the
armature H nears the poles of the magnet this motion is accelerated
by the magnetic attraction, so that rod 6' will strike the pin o³ and
discharge the magnet just as armature H³ reaches its poles, the position
of pin o³ having been so adjusted as to produce this effect. The vibrator
now being free from the attraction of magnet G³ returns again to its
original position by the elastic power of the supporting springs with a
sufficient force to strike pin o' and move point T again on to U2 and
close the circuit for another evolution of the vibrator. In this way
these evolutions will be repeated continuously. Any excess of battery
power is rectified by the cut-off character of the rheotome, thus should
the vibrator in its forward movement receive a greater supply of moving
force than is required barely to break and close the circuit again, it
will return with such momentum as to carry the point T beyond the
point U, and thus break the circuit immediately after closing it.
During the next forward movement of the "vibrator" it will receive
no appreciable accelerating force from the magnet G³, and on its suc-
ceeding return will not drive the bar L³ so far as at its previous return
to this position. At each subsequent return of the vibrator B', b*, to
this point the motion of the rheotome L³ will diminish, till finally the
point T falls on U2, when another accelerating impulse will be given
to the vibrator B', 6'. So prompt and delicate however is the self-
adjustment of this apparatus, that in practice the evolutions of the
"vibrator" will vary only by insensible degrees from that limit of its
vibration which closes the circuit and is just on the point of breaking
it again. An ordinary chronometer balance supported on a "staff” or
on springs, as this vibrator is, may be used to perform all the functions
of a primary, and by substituting the combined feed hand and detent or
other suitable impelling apparatus for the rhcotome, this vibrator in
any of its forms may be used to perform all the functions of a secondary
pendulum.

page_text: When the gyral pendulum is kept in motion by an electro-magnet in
the manner here described, it readily adjusts its own action by a property
of motion inherent in the pendulum itself, so as to compensate for any
ordinary variation in the power of the magnet.
This compensation is effected as follows: Any increase in the pro-
pelling power of the magnet produces an acceleration in the revolution.
of the pendulum. This causes it to gain a small fraction of a second
on the time of its primary, thus carrying the armature H a short
distance beyond the poles of the magnet before it is discharged.
As the armature leaves the magnet while that magnet is yet charged
it is retarded, and this retardation of the armature is equal to a certain
portion of the acceleration which it received while approaching the
poles of the magnet. The surplus of accelerating force (over and above
this retarding force) which the armature receives while approaching the
magnet, is the exact amount required to keep up its gyrations and drive

page_text: immersed in the mercury of cup 7. These cups may be filled above the
mercury surface with the liquid medium before specified.
OPERATION.
As represented in Figure 11 the pendulum is near the right extremity
of its beat, and point T is immersed in mercury in cup S, thus
directing the electric current through wire Nº. As the pendulum
swings to the left point T is immersed in mercury 6 before point T™ is
withdrawn from mercury S, thus securing to the shifter its sparkless
character. As rod 6° moves still to the left point T" is withdrawn from
mercury S, thereby directing a full charge of electricity along the
wire N.
.
DESCRIPTION OF Figure 13.
This Figure represents a form of compound sparkless shifter in which
the electric contacts are made above the surface of the liquid immergent.
I is the crossed lever oscillating freely on the axis Rs and carrying the
movable contact points T and Ts; 9, 10, 11, and 12 are fixed contact
points, cach one forming the terminus of a suitable insulated spring,
to which springs are attached the wires N, N", N", and N" respec-
tively; M and M² are the cups to hold the liquid immergent, which are
so far detached from the contact points that none but the two movable
ones can enter the immergent; G7 and G³ may represent two clectro-
magnetic helices; O³ is a conducting wire which forms electrical con-
nection between the axis R³ and one pole of a battery P³. Wires Nº
and N lead from fixed points 9 and 10 through magnets G' and G³ to
the opposite pole of this battery. Wires N and N connect the corre-
sponding points 11 and 12 directly with the last named pole of the
hattory
OPERATION.
This shifter is put in suitable form to be operated by a swinging
pendulum, which is kept in motion by electro-magnetism. Suppose 3
such to be the case in this instance. The pendulum then is here
supposed to be approaching the limit of its normal swing to the right,
having immersed point T in the liquid contained in cup M³, at the
same time that it raised point T from the liquid in cup M', and
brought it in contact with fixed point 10. This closes the circuit
through magnet G³, which in turn is supposed to actuate the pendulum

page_text: to the left again. As the pendulum nears the left extremity of its beat
point T3 is raised from liquid M and brought in contact with the fixed
point 9, before T has left point 10 in order to avoid the production of
a spark. The several parts must be so arranged and adjusted as to
accomplish this end. If the impulse given to the pendulum during its
last swing to the left has been sufficient to give it more than its normal
amplitude of swing, then point Ts will be urged so far upward as to
come in contact with fixed point 11, and thus complete a short circuit
by which the electric force will elude magnet G' and thus correct the
evil tendency of too much battery power. If the fixed points 11 and 12
and their attached wires be removed then this instrument becomes a
simple current shifter. If further, one of the points 9 or 10 with its
accessories be removed then this instrument will perform the function
of a rheotome, and in each of these supposed cases the advantages of
the liquid immergent or lubricator will be retained.
When many secondary clocks are to be propelled by a single electric
circuit, I interpose between it and the primary pendulum an inter-
mediate electro-magnet, either with or without a pendulum, whose office
and function it is to make and break electrical contact for this extended
circuit by means of electrical impulses from the primary. This arrange-.
ment relieves the primary pendulum of a portion of the work to be done
and thus preserves its timekeeping qualities.
Having thus described the nature of the said Invention, and the
manner in which the same may be carried into effect, I would have it
understood that what I claim is,―
First. The application of the liquid medium or immergent to the
impact surfaces of a rheotrope, shifter, rheotome, or other current
changer, in combination with a pendulum or other timekeeping pulsator,
for the purposes specified.
Second. In the described combination with the electro-magnetic
pendulum I claim the sparkless "shifter" consisting essentially of the
tappets o², o, metallic crossed lever with its permanent central point 1",
and alternating central points T and Ts, together with the mercury
cups 3 and 2 and 4, having suitable connections with magnets Gand G**
and battery P', or devices substantially equivalent.
Third. In combination with the elements of claim second I claim the
additional contact points T and T with their mercury cups 1 and 5, and

page_text: their electrical connections substantially as described, constituting with
said elements the sparkless compound shifter, as and for the purposes
set forth.
Fourth. The described combination of the sparkless
shifter" L-
or L' either simple or compound with a primary pendulum (or other 5
"pulsator") and an electric circuit and its required battery.
Fifth. The described combination of the sparkless shifter I³ or L³
either simple or compound with a primary pendulum (or other pulsator)
and an electro-magnetic helix and a charged electric circuit with its
secondary clock.
Sixth. The interposition of a pendulum or equivalent pulsator (in any
of its forms) between the electro-magnet helix of a secondary clock and
its train of wheels.
1.
Seventh. The described combination with a secondary clock of the
secondary pendulum (or other pulsator) actuated by an electro-magnetic 1
helix isochronously charged.
Eighth. The described combination of a check bar M or its mechanical
equivalent with a secondary pendulum (or other pulsator) actuated by
electro-magnetism when applied to operate a clock movement.
Ninth. The described combination of the feed hand Z and detent St 2
with a pendulum or other pulsator and a clock movement.
Tenth. The combination of the electro-magnetic vibrator (Figure S)
or equivalent pulsator (vibrating in any plane) with the isochronously
charged electric circuit and secondary clock movement.
Eleventh. The described combination of the gyral pendulum with a 2
secondary clock and an electro-magnetic helix isochronously charged.
Twelfth. The described combination of the balance wheel q' or its
equivalent with the impelling fork or its equivalent and a gyral
pendulum, substantially as described.
Thirteenth. The detached lubricating cup or cups (Figure 13) as 3
described in combination with a rheotrope, rheotome, or shifter, and the
electric circuit with its required battery.
Fourteenth. In combination with the corresponding elements of
claim 13 I claim the principal contact points 9 and 10, one or both,
either with or without the additional or "switch-off" points 11 and 12.3

page_text: Fifteenth. I claim the described combination of the impulse spring K³
or its mechanical equivalent with a secondary pendulum or other pul-
sator actuated by electro-magnetism when applied to operate a clock
movement, for the purposes specified:
Sixteenth. I claim the described combination of the impulse weight K
or its equivalent with a secondary pendulum or other pulsator actuated
by electro-magnetism in the described combination with a clock move-
ment, for the purposes specified.
Seventeenth. I claim the secondary pendulum, or equivalent "pul-
sator," with an attached armature vibrating in any plane in combination
with an electro-magnetic helix and an isochronously charged electric
circuit.
Eighteenth. I claim the provision of an electro-magnet (either with
or without a pendulum) interposed between a primary pendulum and
an extended circuit of secondary clocks, as and for the purpose specified.
In witness whereof, I, the said Benjamin Joseph Barnard Mills,
have hereunto set my hand and seal, this Eighth day of October,
in the year of our Lord One thousand eight hundred and seventy-
two.
B. J. B. MILLS. (L.S.)