IMPROVEMENTS IN APPARATUS EMPLOYED IN CONNECTION WITH ELECTRIC TELEGRAPHS, PART OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO ASCERTAIN THE HEAT IN INACCESSIBLE PLACES
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Charles William Siemens at the
Office of the Commissioners of Patents, with his Petition, on the 31st
August 1861. Partly a communication from abroad by Werner Siemens,
of Berlin, in the Kingdom of Prussia.
I, CHARLES WILLIAM SIEMENS, of 3, Great George Street, Westminster, in
the County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN APPARATUS EMPLOYED IN CONNECTION WITH ELECTRIC
TELEGRAPHS, PART OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO ASCERTAIN THE
HEAT IN INACCESSIBLE PLACES," to be as follows:-
It frequently occurs in telegraph wires or cables that are covered by a
sheathing of hemp or iron, and that are piled up in thick coils on board a
vessel or elsewhere, previous to being submerged in the sea, or laid below the
ground, that a spontaneous generation of heat takes place in the before-
mentioned coverings of those wires which are inaccessible to the cooling
influence of the atmosphere. This spontaneous heat, if allowed to increase
unchecked, would soon destroy the insulation of such wires, and render the same
useless for telegraphic purposes. It being impossible to ascertain directly by
means of the ordinary thermometer whether such increases of temperature are
taking place in the interior of such coils of telegraphic wires or cables, the object
of one part of the present Invention is to obtain direct indications of such changes
of temperature by means of an apparatus, one part of which is in direct contact

page_text: with such different parts of coils of telegraph wires or cables of which it is
required to ascertain the temperature, whilst another part of the apparatus is
situated in any convenient place for observation, and is so arranged that the
temperature of such inaccessible places may there be ascertained and read off
with ease on an ordinary thermometer scale. For this purpose a small coil of
insulated copper wire enclosed between two concentric metal cylinders closed
hermetically at each end, and which I term the "thermometer coil," is, in the
first instance, during the coiling up of the telegraph wire or cable placed in con-
tact with such parts of the same, which afterwards become inaccessible, and
ench end of this thermometer coil is connected with other insulated copper wires
leading to the locality where the observations are to be made, where one wire
is connected to one pole of a galvanic battery whilst the other, after forming a
coil round a galvanometer needle is connected to the other pole of the battery.
Thus, an electric current passes from one pole of the battery through the
thermometer coil in contact with the inaccessible portion of the telegraph wire
or cable, thence through the coil round the galvanometer needle, tending to
cause the deflection of the same, and lastly to the other pole of the battery.
Another insulated copper wire is connected to one pole of the same battery, is
then coiled round the galvanometer needle in the reverse direction to the coil
of the first named wire, and passes hence into a vessel or bath containing water
or other fluid, in which an ordinary mercury thermometer is also immersed,
hero the wire is formed into a coil precisely similar to the thermometer coil,
and which I term the "balancing coil," and lastly, it is connected with the
ather pole of the battery.
Thus, a second electric current goes from the first named pole of the battery
through the second coil round the galvanometer needle in the reverse direction
to that of the current in the first named coil, then through the balancing coil
placed in the bath, and lastly to the other pole of the battery. The result of
this arrangement will be, that if the thermometer coil in contact with the
inaccessible part of the telegraph wire, and the balancing coil, placed in the
bath containing water or other fluid, are both of equal temperature, then the
resistance of the one to the passage of the electric current will equal the
resistance of the other, and the galvanometer neodle being in equilibrio, its
position will be marked as zero ou the dial. If now a spontaneous generation
of heat occurs in the covering of the telegraph wire or cable, then this heat
will also be imparted to the thermometer coil in contact with it, and in con-
sequence of this increase of temperature a corresponding increase of resistance
will occur in the same, resulting in the deflection of the galvanometer needle
on one side of the zero point, owing to the currents passing through the two

page_text: galvanometer coils being now unequal. In order to re-establish the equilibrium
of the needle, or to bring it back to zero, it will be evident that the balancing
coil in the bath containing water or other fluid, must be raised to the same
temperature, and consequently to the same degree of resistance as the thermo-
meter coil; this is effected by increasing the temperature of the water or other
fluid in the bath in any convenient known manner until the needle is brought
back to zero point, when the ordinary mercury thermometer immersed in the bath
will obviously indicate the exact temperature, not only of the bath and balancing
coil, but also that of the thermometer coil, and the inaccessible portion of the
telegraph wire or cable with which the same had previously been placed in
contact. It will be evident that any number of the thermometer coils may be
placed at such different points of which it is required to ascertain the tempe-
rature, each coil having its separate conducting wires, which are all brought
to one and the same observing instrument where they can be consecutively
connected with the battery, and coil round the galvanometer needle, and thus
the temperature of each point can be separately determined.
In order to increase the accuracy of the indications of the mercury ther-
mometer, the balancing coil in the bath may be made of a metal of which
the resistance varies in a smaller ratio than that of the metal of which the
thermometer coil is composed, they being, however, so arranged that their
resistances are equal when the needle is at zero; then, for a certain increase
of temperature, and consequently of resistance in the thermometer coil, a much
greater increase of temperature will be required in the balancing coil to bring
the galvanometer needle to zero, and the ordinary thermometer in connection
with the balancing coil will, therefore, give an exagerated reading of the
temperature in the thermometer coil. It will be evident that the above-
described apparatus may be employed for ascertaining the temperature of any
inaccessible places, such as, for instance, the interior of a large body of coal,
hemp, jute, or other substance, of which it is important that the temperature
should be from time to time ascertained.
Also by making the thermometer coil of a refractory metal, such as gold, or
platinum, or an alloy of the same, it may be employed as a pyrometer for
ascertaining the temperature inside furnaces or other places where an intense
heat exists.
In making the pyrometer coil of a metal, the resistance of which varies in a
comparitively small degree, as is the case with German silver and other alloys,
while the balancing coil is made of copper or other pure metal, the resistance
of which varies in a greater proportion; then, if they are so arranged as to be
of equal resistance when the needle is at zero, the indications of the ordinary

page_text: thermometer placed in the bath with the balancing coil will bo a fractional
part of the temperature of the pyrometer, and thus a very long range of
temperature in the pyrometer will be represented by a short range in the
ordinary mercury thermometer.
Another part of this Invention has reference to the manner of printing
despatches in the telegraphic apparatus known as the Morse telegraph.
In the present improvements upon the same, a writing disc is attached to
the end of and moves with the oscillating lever moved by electricity, which
writing disc receives a continuous rotary motion round its axis from the clock-
work of the apparatus, the spindle through which it receives such rotary motion
being provided with an universal joint to allow at the same time of the oscil-
Jating motion of the lever to which it is attached. This writing disc is partially
immersed in a reservoir of ink below, which is capable of adjustment to
maintain the ink at the proper level, the excess of the ink which is carried up
during the revolution of the disc being lightly scraped off the circumference of
the latter by a small scraper attached to the oscillating lever. The paper is
led over a fixed pin or small roller situated directly over the tracing disc, it
being made to travel in a direction contrary to that of the revolution of the
writing disc by means of drawing rollers moved by the clockwork. By the
oscillations of the lever the tracing disc is at intervals pressed up against the
paper, thus marking it with a distinct ink line. Instead of allowing the writing
disc to fall back into the ink or upon an inked surface in connection with a
bird's fountain or other reservoir, an endless cord or chain may be employed,
passing over a second roller and dipping on its way into the ink or passing in
contact with an inked surface.
The chief peculiarity of the just-described arrangement is, that the revolving
writing disc is made capable of being moved against the paper whilst the latter
is tightly stretched over the small curvature of a fixed pin or small roller,
where it is capable of receiving a very sharp impression, and is entirely
relieved again from contact with the writing disc by an exceedingly short
traverse of the latter, it being a point of great advantage in telegraphy to
obtain distinct signals by the least possible motion of the armature. In
scraping the edge of the writing disc as the same revolves, any accumulation
of dirty ink upon the same is prevented, by which the effective state of the
instrument is preserved.