Year: 1887

page_text: I WILLIAM HENRY DOUGLAS of Stourbridge in the County of Worcester Watch-
maker do hereby declare the nature of this invention to be as follows:-
This invention consists in creating heat in proportion to the current by resistence
in the coil and placing in near proximity thereto a thermometer which will by
indicating the temperature show the intensity of the current. The normal tem-
perature of the atmosphere being indicated by another thermometer so that the
difference between the registration of the two thermometers will indicate the intensity
of the current. To obtain a permanent registration of the movements of the therino-
meters I have a strip of paper moved by a motor upon which the hand or hands of
the thermometers are made to leave a record.
PAYNE & TALBOT,
7, Cherry Street, Birmingham,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION..
An Improved Meter for Measuring Electrical Currents.
WILLIAM HENRY DOUGLAS of Stourbridge in the County of Worcester Watch-
maker, 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, reference being had to the accompanying drawings and to the letters and
figures marked thereon:-
This invention consists in creating heat in proportion to the current by resistance in
the coil and placing in near proximity thereto a thermometer which by indicating the
temperature shew the intensity of the current, the normal temperature of the
atmosphere being indicated by another thermometer so that the difference between
the registration of the two thermometers will indicate the intensity of the current.
By connecting the two thermometers by a differential gearing of wheelwork a hand
can be made to shew upon a dial the difference of the two thermometers and thus
indicate the intensity of the current.
To obtain a permanent registration of the movements of the thermometers I may
have a strip of paper moved by a motor upon which the hand or hands of the thermo-
meters are made to leave a record. Or instead of obtaining a permanent record by
means of a strip of paper as above described I can obtain a permanent record in the
following manner.
The two thermometers are connected by means of a lever attached to each these
levers are connected by means of a differential gearing of wheelwork. The electric
current is then made to pass through one of thermometers, the resistance to the
current by the thermometer is then indicated by means of a snail placed upon the
differential gearing.
The heat increasing as the square of the current is registered by means of the
divisions upon the snail a lever with a gathering click attached to it is made to fall
upon the divisions of the snail at intervals, a clock or motor is then made to lift the
lever and gather up the number of teeth of a ratchet wheel corresponding to the
number indicated by the division of the snail the number is then recorded by hands
upon a dial.
Iis not necessary to pass the current through the thermometer as above described
but I find it the most economical way of obtaining the desired result.
Referring to the drawings in which similar letters of reference relate to similar
parts.
Fig. 1 illustrates two thermometers (A) and (B) both recording normal temperature
(C) is a coil placed round the one thermometer (A) so that when an electric current
passes through the coil it raises the temperature round the thermometer.
The amount of electricity that has passed through the coil being indicated by the
difference of the record of the two thermometers (A) and (B).
Fig. 2 represents two thermometers (D) (D) of compound wire with levers (E E¹)
attached to them the said levers connected to a differential gearing of wheel work (F)

page_text: An electric current caused to pass through the wires (W) into the coiled thermo-
meter (D) heats it (the heat increasing as the square of the current) and expands
the wire coil in proportion thereto carrying the lever E¹ with it the expansion of the
compound wire thermometer D not being in connection with the electric current is
only affected by the temperature of the atmosphere and the lever (E) only moves to
that extent. The differential gearing (F) will then shew the difference between the two
thermometers, the amount of this difference being indicated upon a dial such as
shewn in Fig. 3 by means of the hand (Y) connected with the differential gearing.
The thermometers are kept in tension by the weights (G G) Figs. 4 and 5 are front
and side views of one construction of my apparatus in conjunction with a self winding
clock (Z) (a a) are two thermometers consisting of two coils of compound wire these
thermometers are connected to differential gearing by means of the levers (bb) these
levers (bb) acting upon the differential gearing (c) (d) is the snail upon the differential
gearing (c) having the divisions (e) upon it (f) is a lever with a gathering click (g)
attached to it and placed so as to fall upon the divisions (e) of the snail (d).
The click (9) gathers the number of teeth of the ratchet wheel (h) corresponding to
the number of the notch or division upon which the lever (f) has fallen. The number
of teeth so gathered is then recorded by the hour hand upon the ampere dial (i) Fig. 6
by the train of motion wheels (1) Fig. 4.
The lever is raised by the clock movement (1) at intervals by the wheel (K)
which carries a pin for the purpose.
This gathering lever (f) may be raised at intervals by any suitable motor or clock
that which I have illustrated being an electrical self winding clock.
Fig. 6 shews a dial arranged as a recorder of time and the measurement of the
electrical currents.
(m) (n) and (o) are the ordinary hour minute and seconds dials of the clock (p)
and (g) are dials shewing the ampere hours the hand of the smaller dial (p) recording
one hundredth part of the larger dial (g).
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.
1st. An improved meter for measuring electrical currents consisting of the use of
two thermometers one of which is affected by the electrical current.
2nd. Connecting two thermometers by a differential gearing of wheelwork whereby
the quantity of electrical current passing is indicated by means of a hand upon a
dial.
3rd. The introduction of the snail for the purpose of measuring electrical currents.
4th. The general combination of thermometers and clock work substantially as herein
set forth for the purpose of measuring electrical currents.
Dated this 321 low of Lun 1000
PAYNE & TALBOT,
7, Cherry Street, Birmingham,
Agents for the Applicant.