Improvements in Apparatus for Obtaining a Record of the Move- ments of Indicators by Means of Electricity.
Year: 1889

page_text: Date of Application, 18th Dec., 1889-Accepted, 8th Mar., 1890
Improvements in Apparatus for Obtaining a Record of the Move-
ments of Indicators by Means of Electricity.
I, THOMAS JOHN MURDAY, of Felton, in the County of Northumberland, Electrical
Engineer, do bereby 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 has for its object improvements in apparatus for obtaining, by
means of electricity, a continuous record from a distance of the indications or move-
ments of instruments or indicators such as steam-pressure gauges, anemometers,
aneroid barometers and the like, which are provided with an index or pointer moving
over a scale.
And in order that my invention may be thoroughly understood I have appended
the accompanying sheets of drawings.
Figs. 1 and 2 aro front and side elevations respectively of the apparatus, in what
may be called the distant station, where the in-ticator is placed.
Fig. 3 is an end elevation of part of the apparatus in the distant station.
Fig. 4 is a front elevation of the apparatus, in what may be called the home station,
where the record is made.
Fig. 5 is a diagram showing the electrical connections in both the distant and
home stations.
In these Figures similar letters of referenco indicate corresponding parts, and
some of the parts of the apparatus are omitted in the Figures for the sake of
clearness.
In the distant station A is the scale of the indicator. B is the index or pointer
moving over the scale A. The arrangement of magnets and the rest of the apparatus
is placed in front of the indicator. C is a brass or other standard, which serves as
bearings for the shaft on which are mounted a ratchet wheel and a pinion D, which
latter engages with a toothed sector E. The said ratchet wheel is a double ratchet
wheel, that is to say it consists of two separate ratchet wheels F, F, placed side by
side but with their teeth set in opposite directions. For the sake of clearness, only
one set of teeth is shown in Fig. 1, but in Fig. 2 both ratchet wheels are shown,
and in Fig. 4 whore a corresponding double ratchet wheel is shown, the two separate
wheels are drawn, one of them being inked in black and the other left white. The
pawl H of the pivotted armature 1 acts upon the ratchet wheel F, and the pawl J
of the pivotted armature K acts on the other ratchet wheel F₁. The pawls Hand J
of the pivotted armatures I and K give opposite motions to the shaft upon which
the double ratchet wheel F F, is mounted, the direction of which motion will depend
for the time being upon which of the two pawls is in action, or in other words
will depend upon whether the current is circulating through the winding of the
electro-magnet L or that of the electro-magnet M. The pawls H and J of the
pivotted armatures 1 and K are kept out of action, when no current is passing
through the windings of the electro-magnets L and M, by means of springs. The
axis upon which the toothed sector E is mounted is carried by the standard O, and
the axis is prolonged so as to approach the axis of the indicator, and upon such
prolongation is fixed a short cylinder N of ebonite or other insulating material.
Upon the cylinder N, and separated from each other, are fastened two metallic
segments O, O₁, which are provided with pointers P, P. The pointers P, P₁ are
fixed to the segments 0, 0, so as to be parallel to each other, and are only
separated from one another by a small space. In practice it is found most suitable
to have the movement at each contact not to exceed one twentieth of an inch. The
ends of the pointers P, P₁ are provided with platinum contacts p, and to the index

page_text: or pointer B is attached a platinum wire B₁ which works between the two
pointers P, P, and touches the platinum contact on one or the other of them
according to the direction in which the pointer B of the indicator moves. Two
springs, press upon the metallic segments 0, 0₁. One end of the winding of
the electro-magnet L is connected to the spring Q, and the other end of the same
winding to the binding post 1. One end of the winding of the electro-magnet M
is connected to the spring Q and the other end of the same winding is connected to
the binding post 2.
The arrangement of apparatus in the home station-which is very similar to that
in the distant station-is as follows.
2
C₁ is a brass or other suitable standard, which serves as bearings for the shaft upon
which are mounted the double ratchet wheel F2, F, and the pinion D₁, which latter
engages with the toothed sector E₁. The pawl H₁ of the pivotted armature I, acts on
the ratchet wheel F₂, owing to the downward pull of the electro-magnet L₁ and drives
it in one direction; and the pawl J₁ of the pivotted armature K₁, owing to the down-
ward pull of the electro-magnet M₁, acts on the ratchet wheel F, and drives it in
the direction opposite to that in which the ratchet wheel F, is driven. The toothed
sector E, is attached to a pivotted lever R, one end of which is weighted and the other
end carries a pencil or other marker S, kept in continual contact with a band of paper
or the like wound upon a rotating druin T. The drum T is rotated at any desired
rate, say at such a speed as to make one revolution in seven days, by means of clock-
work or other suitable mechanisın. When the shaft of the double ratchet wheel F, F,
is driven in one direction by the action of the pawl H, the marking end of the
weighted lever R will be raised, and when it is driven in the opposite direction the
said marking end will be lowered.
One end of the winding of the electro-magnet L, is connected to the binding post 1
and the corresponding end of the winding of the electro-magnet M₁ is connected
to the binding post ; the other ends of the windings of the electro-magnets L
and M, being connected to a common binding post 3. The binding posts 1 and 1 in
the home and distant stations are connected to each other, and the binding posts 2
and 2 of the stations are also connected to one another. One pole of the battery, used
for supplying the current to work the apparatus, is connected to the binding post 3,
and the other pole of the same is connected to the metal work of the indicator, as
at X, Fig. 2.
Fig. 5 shows, diagrammatically, the arrangement of the electrical connections, the
parts shown therein being designated by the same letters as the corresponding parts in
the apparatus, already described. From this diagram and from the foregoing
description it will be seen that there are two distinct circuits through the apparatus
and that the circuit through which the current passes will depend upon which of the
two pointers of the metallic segments is in contact with the hand of the indicator.
The action of the apparatus is as follows:-
As long as the index of the indicator does not touch either of the pointers P, P₁
the circuits are open and no current flows. If the index of the indicator falls (or
moves against the scale) slightly and touches the pointer P then this contact completes
the circuit through the electro-magnets M, M, and causes the armatures K, K₁ to be
pulled downwards and drive the shafts of the double ratchet wheels F F₁, F, F, in
one direction. This motion is transmitted by the pinions D, D₁ and toothed
sectors E, E, to the pointers P, P, and the weighted lever R, the motion of which
latter causes a corresponding mark to be made upon the paper on the rotating drum T.
The pointer P is thus lowered out of contact with the index of the indicator, the
pointer P₁ brought correspondingly near to it, and the circuit simultaneously broken.
Should the index of the indicator continue to fall, another_contact with the pointer P
will take place, and similar movements of the pointers P, P, and the weighted lever R
will take place. On the other hand, when the index of the indicator rises (or moves
with the scale) slightly contact is made with the pointer P₁ and this contact com-
pletes the circuit through the electro-magnets L, L₁. The pointers P, P, are then
caused to move also with the scale, and a motion is given to the weighted lever R in
1

page_text: the opposite direction to that in which it was moved when the current passed through
the other circuit. The opposite motions given to the weighted lever will cause the
pencil or other marker at the end of the same to trace a zig-zag or wavy line, which
will present an accurate and continuous record of the indications or movements of
the band of the indicator.
In the accompanying drawings I have shown a scale which is only a segment of a
circle, but the apparatus could be easily arranged and modified so that the record
should be that of the movements of the index of the indicator over the greater part
or the whole of a circle.
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
claim is :-
The apparatus for obtaining by means of electricity a continuous record of the
indications or movements of the index hands or pointers of indicators such as
steam-pressure gauges, aneroid barometers, anemometers and the like, substantially
as described herein and illustrated with the aid of the accompanying drawings.
D
1000
JAMES STEVENSON,
Gray's Inn Chambers, 20, High Holborn, London, W.C., Agent for Applicant.