IMPROVEMENTS IN APPARATUS FOR MEASURING AND REGISTERING ELECTRIC CURRENTS
Year: 1882

page_text: LETTERS PATENT to Alexander Login Lineff of Wilmington Square in the
County of Middlesex for an Invention of "IMPROVEMENTS IN APPARATUS
FOR MEASURING AND REGISTERING ELECTRIC CURRENTS"
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said Alexander Login Lineff at
the Office of the Commissioners of Patents on the 31st August 1882.
ALEXANDER LOGIN LINEFF of Wilmington Square in the County of Middlesex,
IMPROVEMENTS IN APPARATUS FOR MEASURING AND REGISTERING
CURRENTS
"
ELECTRIC
For indicating the strength or measuring the quantity of electricity passing
through any given circuit I have devised an apparatus or instrument which I call
a hydraulic electric dynamometer and which is arranged as follows:-
A bobbin wound with stout insulated wire is put in the circuit whose current is
to be measured. Inside this bobbin is placed one branch of a glass tube bent in
the form of the letter U; the other branch is outside the bobbin and of much
smaller diameter. This tube is filled to a certain height with mercury and an iron
float is put on the surface of the mercury in the inside branch. When the current
passes through the bobbin it causes the float to descend towards the centre of the
bobbin to an extent corresponding with the strength of the current. It thus acts
like a piston and presses upon the mercury forcing it up the outside branch. The
outside branch being of much smaller diameter magnifies the rise and fall of the
iron float to any desired extent in the outside branch, thus making the instrument
very sensitive. The outside branch is graduated each division corresponding to
one ampère or a certain part of it the zero mark corresponding to the normal
position of mercury when there is no current in the bobbin. The other
divisions, corresponding to one, two or more ampères should be marked by
experiment for each instrument. The surface of mercury in both branches
should be protected from evaporation by a thin layer of glycerine or other suitable
fluid.

page_text: Any other fluid than mercury can be used, and even with better result because
the specific gravity of mercury being very high more pressure is required to raise
the level in the outside branch, in fact mercury makes the instrument less
sensitive.
In order to obviate this, I sometimes fill the outside branch above the mercury
with glycerine and make the pipe at a certain distance from the level of mercury
of a much smaller section. Thus any alteration of the level of mercury is magnified
firstly in proportion to the ratio of the large and small sections of the pipe and
further multiplied by the ratio of specific gravity of mercury to that of glycerine
or other fluid that is used.
I sometimes use the glycerine alone but in this case it is preferable to have the iron
float hollow and moreover suspended on an elastic membrane of india rubber or
other suitable material.
The hydraulic electric dynamometer before described may be used also for
continuous registration of the strength of current in a manner similar to those
used for Barographs, Thermographs and similar instruments by means of a beam
of light passing through the outside tube and recording the height of the mercury
on a revolving cylinder covered with sensitive paper thus giving a continuous
record of the quantity of current passing through any given circuit.
In this case
it becomes an electric meter.
In the instrument above described the degrees marked on the outside branch
and corresponding to 1, 2, 3 ampères will be unequal, diminishing with the strength
of current. But it is easy to make the distance between each two marks equal by
giving to the glass tube such shape that the volume of mercury between every
two divisions will be proportional to the increment of the quantity of current. If a
second float is put on the surface of the mercury in the outside branch, the rise of
such float will be exactly proportional to the quantity of current. Now if such
float is connected with a valve through which water can run, it will regulate the
flow of water exactly in the same ratio as the current in the bobbin. Thus the
quantity of water passing through the valve will record the quantity of electricity
passing through the circuit.
Instead of the arrangement with a double bent tube and a float I use for the
electric current meter an ordinary iron core which rises or falls with the variation
⚫ of the current in the circuit. The above core is connected by means of a rod or
other suitable lever arrangement with the valve that regulates the flow of water.
In order to make the opening of the valve proportional to the strength of current
the rod attached to the core is provided with teeth that gear into a pinion on a
spindle. To this spindle is fixed a toothed sector of such shape that the rack
gearing with it and connected with the regulating valve causes the latter to open
in direct proportion to the strength of the current in the bobbin.
Any system of valves may be used for regulating the flow of the water, but for
many reasons I prefer the equilibrium valve, by the use of which no extra pressure
is created when the flow of water increases.
In order to have the water running through the above regulating valve perfectly
pure, I place in my meter a filter of such construction, that by turning a separate
cock, the filter may be cleansed in a few minutes without interfering in the least
with the working of the apparatus. From the filter the water passes into a small
reservoir with a constant level, so that the water comes to the valve box under
constant pressure.
The quantity of water flowing through the valve is measured in the ordinary
way.