A New. or Improved Secondary Clock.
Year: 1888

page_text: Date of Application, 31st Dec., 1888
Complete Specification Left, 30th Sept., 1889-Accepted, 2nd Nov., 1889
A New. or Improved Secondary Clock.
I, JAMES GRIEVE LORRAIN of Norfolk House, Victoria Embankment, London, W.C.,
Consulting Engineer, do hereby declare the nature of this invention to be as
follows:-
In the Complete Specifications accompanying my Letters Patent Nos. 8181 of the
year 1886 and 9264 of the year 1887 I have described forms of secondary clocks
actuated by electromagnets.
My present invention differs therefrom in that instead of causing the hands to be
moved and the time to be indicated by the action of an electromagnet upon its
armature I cause the said action to take place through the expansion of a con-
ductor on each passage through it of an electric current the said expansion causing
the movement of the hands through the intervention of any convenient mechanical
transmitting mechanism.
I may employ a detent for the purpose of limiting or controlling the movement
produced.
COMPLETE SPECIFICATION.
A New or Improved Secondary Clock.
1, JAMES GRIEVE LORRAIN, of Norfolk House, Victoria Embankment, London, W.C.,
Consulting Engineer, do hereby declare the nature of this invention and in what
manner the saine is to be performed to be particularly described and ascertained in
and by the following statement:—
In the Complete Specifications accompanying my Letters Patent Nos. 8181 of the
year 1886 and 9264 of the year 1887 I have described forms of secondary clocks
actuated by electromagnets.
My present invention differs therefrom in that instead of causing the hands to be
moved and the time to be indicated by the action of an electromagnet upon its
armature I cause the said action to take place through the expansion of a con-
ductor on each passage through it of an electric current the said expansion causing
the movement of the hands through the intervention of any convenient mechanical
transmitting mechanisın.
I may employ a detent for the purpose of limiting or controlling the movement
produced.
Having thus described in general terms the nature and object of my invention
I shall now proceed to describe in what manner it is to be or inay be carried into
effect and for this purpose I shall describe by way of a type or example one way
of performing my invention. In order that such description of the type or example
which I have selected for mention herein may be more readily understood I have
annexed hereto a drawing illustrating the essential parts of my invention as applied
to the said type or example.
The accompanying figure illustrates a convenient method of, and combination of
devices for, carrying my invention into effect. In the figure A represents the main
wheel that is to say the first of the train of wheels actuating the hands. B is a
thin metal wire rigidly fixed at one end to the cock or terminal plate C whilst its
other end is attached to the weighted lever D. This lever turns freely on the
arbor a', on which the main wheel is rigidly mounted, and bears the click or

page_text: pawl E which gears into the teeth of the ratchet wheel H which like A is also
rigidly mounted on the arbor a¹.
The action of the parts just mentioned is as follows. The clock is connected up
in the usual. way and an electric current: is transmitted through itvat intervals for
the purpose of moving the, hands: through the,required angular distance. In the
figure I have shown the course of the current as being from through B and part
of D to a and thence to the exterior of the clock to the line wire. Let us now
assume that a current is transmitted. In passing through B which is of such material
and so thin as to offer a considerable resistance the current raises the temperature
of B and so causes it to expand. This expansion of B causes the weighted lever D
to descend and the pawl E to engage with the teeth.of the ratchet wheel Fl and
carry the latter round through a. part of a revolution. The current ceasing now to
be passed the wire B will cool and in cooling will shrink so as to bring the lever D
back into its normal position. as shown in the figure whilst the click G will prevent
any backward movement, of the ratchet wheel H. With the backward movement
of the lever D the pawl E will rido loose over the teeth of H and the parts will
again. be in their normal. position and ready to go through a similar cycle of move-
ments at the next transmission of the electric current.
If the clock has been very carefully constructed and the parts adjusted with great
nicety the click Gmay be dispensed, with but I do not recommend this as the click is
always a useful safeguard.
If care be taken to transmit, only the proper current and for the proper length of
time the hands will be moved through the proper angular distance each time the
current passes but inasmuch as in practice clocks would constantly be added to and
removed from the circuit so, that the current would require to be altered acccordingly
I prefer instead of adapting the current to suit the clocks after each change in the
circuit to so fit the clocks with controlling devices that the hands will always be moved
through the required angular distance without reference to the exact conditions of the
current or of the circuit. This definite amount of movement I secure by means of the,
detent F, in this case shown as a set-screw, which limits or stops the descent of D
after a definite amount of movement has taken place and this quite irrespective of the
amount, of expansion and of current, but always provided that the current be sufficient
to cause, expansion until the detent is reached by the lever. Any margin of current
beyond this amount will produce no further movement of the hands. As a further
safeguard for securing that the amount of movement shall be definite I generally
employ a second'dëtent whichi,may conveniently consist of a pin J. The function of
this detent is to limit the movement of the hands to the required amount by ensuring
that in the backward movement of the pawl to its normal position it shall not take
too large a feed, as it is termed, that is to say, it shall not come back so far as to
engage a tooth of the ratchet wheel further back than that tootli' which when moved
forward. to the proper limit of movement shall cause the proper amount of angular
movement of the hands. By such means the action of the clock is protected from any
error due to change of external temperature for it will be readily seen that a fall of
temperature when the current is not passing would but for this dêtent J'cause such a
contraction of the wire B as to cause the pawl to take a larger feed at the next trans-
mission of the current and so produce a greater movement of tlie hands than is
desired.
It will be seen that at each transmission of the electric current a definite move-
ment of the expanding conductor takes place and that this imparts a definite amount
of movement through the train of wheels to the hands. In practice I find it con-
venient to transmit the current from the master clock for a period of one second every
half-minute and I adopt a train of wheels in accordance with this so that the long hand
is.moved round through one one-hundred-and-twentieth (10) of the circumference of
the dial or in other words through an angle of 3 degrees at each movement; the short
hand being, moved through a proportionate distance. The dimensions of the various
parts hereinbefore described vary with the size of the clock and the power required

page_text: to actuate it. In the case of an ordinary secondary clock as inade with a dial about
twelve inches in diameter, a platinum wire of about two mils. diameter and about
six feet long will give good results. Such a wire may be heated by a current of
about one ampère. The weight of or on the lever should be but little in excess of
what is required to actuate the train of wheels and hands. The position of attachment
of the wire to the lever may be varied to suit the conditions of working. Thus if a
large current be supplied a shorter and thicker wire attached closer to the fulcrum
may be used but it should be borne in mind that the thicker the wire the fewer must
be the transmissions of the current within a given time or the shorter will be the
amount of movement of the wire at each transmission as a thick wire necessarily takes
longer to cool and contract than a thin one.
The clock case need not be made of great length to accomodate the wire. It may
be of ordinary form with a tube to contain the wire standing up from it. Or, the
wire instead of being straight may pass over pulleys of non-conducting material so
as to be bent, coiled or otherwise arranged in small compass.
In the type or example of my invention which I have described it is the expan-
sion of the wire which enables the weight to do the actual work of moving the
train of wheels and hands. As is self evident however the action might conveniently
he reversed so that it would be the contraction which would be used to actuate
the train of wheels and hands, the expansion merely serving to take the feed. In
this case the position of F and of J' would be reversed as would the direction in
which E and the teeth of H point; and the wire, lever, detents and pawl would be
arranged at the other side of the arbor a' from that shown in the drawing. The lover
would then need to be only sufficiently weighted to take up the slack of the wire
as it expanded or in other words keep it taut.
The ratchet wheel and pawl arrangement for transmitting the movement of the
wire to the train of wheels actuating the hands is a convenient contrivance for the
purpose but equivalent devices will readily suggest themselves to mechanics. The
same remark applies to the weighted lever.
The type or example which I have described illustrates the best means with which
I am acquainted for the carrying into effect of my invention. Other ways, of utilising
the expansion of a conductor in accordance with my invention may be adopted if
desired and without departing therefrom. Many ways, such for example as the utilisa-
tion of the movement of a thermostatic band consisting of a compound strip of two
metals soldered together and having different coefficients of expansion under rise of
temperature, or the utilisation of the expansion of a metal ring through which passes
a conical plunger so that the more the ring expands the further will the plunger pass
through it or the utilisation of the expansion of a mercury column, are obvious
equivalents which would at once occur to the mind of any qualified electrical engineer.
In the figure it will be seen that the weight of or on the lever (a spring would be
an obvious equivalent for the weight) takes up the movement of the conductor so that .
the said movement can be utilised to produce the movement of the hands.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
clatin is :-
1. In a secondary clock the method of actuating the hands by utilising the expan-
sion of a conductor produced by an electric current substantially as set forth.
2. In a secondary clock the employment of an electrically expanded conductor as a
motor substantially as set forth.
3. In a secondary clock the combination of an electrically expanded conductor and
a weight or spring for taking up the movement of the said conductor so that the said
movement can be utilised for the purpose of moving the hands.
4. In a secondary clock actuated by an electrically expanded conductor the means
of securing a definite amount of movement substantially as set forth.
5. In a secondary clock actuated by an electrically expanded conductor the employ-
ment of a detent substantially as and for the purpose set forth.

page_text: 6. In a secondary clock the combination of an electrically expanded conductor, a
weighted lever, a pawl, a ratchet wheel and a train of wheels for actuating the hands,
substantially as set forth.
J. G. LORRAIN.