Improvements in and relating to Electrical Pendulum Contacts for the Operation of Time Measuring Pendulums
Year: 1899

page_text: Date of Application, 15th June, 1899-Accepted, 29th July, 1899
Improvements in and relating to Electrical Pendulum Contacts for
the Operation of Time Measuring Pendulums,
A communication from abroad by Dr. L. SELL, of 22, Dorotheenstrasse, Berlin,
in the German Empire, Consulting Engineer.
I, ALFRED GEORGE BROOKES, of 55 and 56, Chancery Lane, in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:—
This invention relates to a device for the direct electrical operation of time
measuring pendulums. It is based upon the utilization of the influence which
power of inertia and frictional contact with the surrounding walls exert upon
the motion of mercury contained in a vessel swinging with a given pendulum:
Some of the forms in which the invention may be carried out are shown by
way of example in Figs. 1 to 4 of the accompanying drawings.
To the pendulum rod 1' there is secured a glass tube bent in the shape of either
a ring or a rectangle, so that its ends are directed towards each other, and that
its two upright or rising arms come to be situated on either side of the pendulum
rod in the plane of its oscillation. Into these arms are blown enlargements a,
while platinum wires b, c, extending in the downward direction from above, are
fused into such arms; one of such wires, say the right hand one, c, reaches down to
the middle of the corresponding enlargement, while the other left hand wire, b,
descends lower. The outwardly projecting ends of the platinum wires are placed
in contact with current supplying binding screws through the medium of flexible
wire-loops. The vessel is half filled with mercury, while from the remaining
portion the air is exhausted and it is assumed that the angle of inclination of the
vessel to the pendulum-rod is so adjusted that, while the pendulum is at rest,
the end of the right hand wire just touches the surface of the mercury, while
the end of the left hand wire constantly remains immersed.
Supposing now that a swinging movement is imparted to the pendulum and
that the mercury only moves under the influence of gravity: the plane of the
mercury-levels will invariably remain horizontal and the platinum points unless
they should display any marked phenomena of adhesiveness-will enter or leave
the mercury (as the case may be), whether the pendulum be moving in one or
the other direction, whenever it moves past its central position. This method
of making contact would however be unserviceable or disadvantageous for pur-
poses of the direct electro magnetic operation of a pendulum because (to say
nothing of the displacement which assuming magnetism to be present-would
be caused by the magnetic inertia of the iron, but which are scarcely deserving
of any notice here) the pendulum receives as much power in receding, as it
gathers in advancing.
But in point of fact, in consequence of the shape of the vessel adopted in the
present instance, the motion of the mercury is to a material extent influenced
by its vis inertiae and by friction, as it passes through the portion of the tube

page_text: which connects the two balls. The result is such a phase displacement in the
motion of the mercury, relatively to the motion of the pendulum, that, as the
pendulum swings from the left to the right, for example, the point of the wire
will plunge into the mercury at the moment of such pendulum passing through
its middle position, while it will not so plunge when the middle point is passed
in the course of the return movement of the pendulum.
By reducing the width of the lower junction tube more or less the extent or
amplitude of that displacement may be increased or diminished both as to space
and time; and this mode of making contact is admirably suited to the electrical
operation of the pendulum, all the more because the phenomenon just described
will invariably occur, no matter how slight the oscillations may be. By such
means, therefore the pendulum can be made to start automatically, a result
which for a variety of purposes will prove exceedingly valuable, as, for example,
for all counting or recording devices in which the duration of the current supply
is a factor to be reckoned with, such as time recorders, ampere-meters, Watt-
hour-counters, meteorological recording instruments mounted in inaccessible
situations, level-recorders, and the like.
Besides, it is a well known fact that the continuity of operation of any clock-
work is far more reliable than it would otherwise be, if only a minimum initial
impact, or none at all, is necessary for starting it.
Electro magnetic operation may be provided for in various ways: for example,
it may take the shape of a mechanical arrangement which will only act within a
predetermined angle of oscillation, and the operation of which will consequently
not extend beyond a certain limit of time determined by the duration of the
contact. But the most simple-and sufficient arrangement will be one in which
the armature of an electro magnet is allowed to act direct upon a lever arm
secured to the pendulum, or in which the armature is attached to the pendulum
itself, as in Hipp's well known clocks and similar apparatus, where all that is
necessary is to provide for a free outward swing. A train of gear wheels may be
operated either by the armature or by the pendulum itself. The contact switch
may be constructed either for short circuiting or for contact-breaking, and be
arranged, if desired, above the suspension.
Of other possible forms of vessels, those represented in Figs. 2 to 4 may be
described.
The arrangement illustrated in Fig. 2 only differs from that shown in Fig. 1
in the asymmetrical position of the inwardly curved mercury tube. In the case
of the vessel depicted in Fig. 3 the top connection is omitted: the portability
of this form of apparatus pre supposes a high degree of vacuum.
While the
modification illustrated in Fig. 4 displays one connected mercury level. The
necessary check upon the alternating flow of the mercury is provided for by an
adequate reduction of the sectional area of the central portion of the vessel.
It is not necessary for the line of longitudinal section of the vessel to coincide
with or be parallel to, the plane of oscillation, as has thus far been assumed to
be the case.
Indeed by making that line capable of varying its relative position
to the pendulum-axis, a means may be afforded for adjusting the effective distance.
Neither need the vessel necessarily be secured to the pendulum itself, but it
may be connected therewith by any suitable mechanical means, provided always
that it oscillates in such a manner that the phase-displacement above described
takes place.
It will be understood that a balance operating under the action of a spring may
be substituted for the pendulum.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a
new and improved time measuring pendulum with means for

page_text: swinging with such pendulum and partly filled with mercury; of a conductor
placed in permanent metallic contact with the mercury of the vessel named and
connected to a source of electricity; and of a second conductor which is so
arranged that, as the pendulum swing backwards and forwards, the said con-
ductor, at different phases of the swinging motion, dips into and emerges from
the mercury; substantially as and for the purpose specified.
2. In a new and improved time measuring pendulum with means for its elec-
trical operation, the combination with the pendulum of a vessel secured to the
pendulum rod and partly filled with mercury; of a conductor placed in permanent
metallic contact with the mercury; and of a second conductor which is so arranged,
that as the pendulum oscillates, it periodically dips into and emerges from the
mercury; the said vessel, in its central portion, being elongated or reduced in
width, whereby a check is placed upon the backward and forward flow of the
mercury, substantially as and for the purpose specified.
3. In a
new and improved time-measuring pendulum with means for its
electrical operation the combination with the pendulum of a vessel partly filled
with mercury and connected with the pendulum rod; of a conductor placed in
permanent metallic contact with the mercury contained in the said vessel and
connected to a source of current; and of a second conductor which is so arranged,
that, as the pendulum oscillates, it dips into and emerges from the mercury; the
said vessel, containing the mercury, being capable of revolving in its plane of
oscillation, and being furthermore adjustable in such a manner that the point of
the conductor, extending into the vessel, just touches the surface of the mercury
or is at any optionally variable short distance therefrom, substantially as and
for the purpose specified.
WM. BROOKES & SON,
55 and 56, Chancery Lane, London,
Agents for the Applicant.