New or Improved Apparatus for Enabling Temperatures to be Ascertained at a Distance.
Year: 1888

page_text: Date of Application, 22nd Dec., 1888
Complete Specification Left, 23rd Sept., 1889-Accepted, 26th Oct., 1889
PROVISIONAL SPECIFICATION.
New or Improved Apparatus for Enabling Temperatures to be
Ascertained at a Distance.
I, JAMES GRIEVE LORRAIN, of Norfolk House, Victoria Embankment, London,
W.C., Consulting Engineer, do heroby declare the nature of this invention to be as
follows:-
The principle of my invention lies in the utilising of the alterations of volume or
pressure of a suitable expansible fluid, produced by alterations of temperature at the
place whose temperature is required to be known, to cause alterations of the resistance
in an electric circuit: so that a suitable galvanometer, placed in or in connection with
the said circuit, and at the place where it is desired that the temperature should be
made known, shall, under the influence of such alterations as aforesaid, indicato the
temperature for the time being at the distant place where the expansible fluid is
situated.
It is obvious that there are many ways in which, and many structural details by the
aid of which, my invention, whose nature I have just described, may be performed;
but these need not be specified here.
COMPLETE SPECIFICATION.
New or Improved Apparatus for Enabling Temperatures to be
Ascertained at a Distance.
I, 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 same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The principle of my invention lies in utilising the alterations of volume or pressure
of a suitable expansible fluid produced by alterations of temperature at the place
whose temperature is required to bo known to cause alterations of the resistance in
an electric circuit so that a suitable galvanometer placed in or in connection with
the said circuit and at the place where it is desired that the temperature should be
made known shall under the influence of such alterations as aforesaid indicate the
temperature for the time being at the distant place where the expansible fluid is
situated.
Having now briefly specified the general scope of my invention I shall now proceed
to describe as types or examples a few ways in which it may be performed or carried
into effect and for that purpose I shall refer to the accompanying drawings.
In figure 1, A is a thermometer tube containing mercury in the usual manner.
Down the tube and dipping into the mercury is a fine platinum wire a¹.
B is a
primary battery or other source or reservoir of electrical energy and Ca galvanometer.
These devices are preferably connected up electrically as shown. That is to say, a
lead w sealed through the bulb of the thermometer and passing to one pole of the
battery places the mercury in electrical connection therewith. The other pole of the
battery is connected by a lead with one terminal of the galvanometer. The other
terminal of the galvanometer is connected by a lead to³ with the platinum wire a¹.
The thermometer is situated at the place the temperature at which it is desired to
know. This place I shall hereinafter refer to as the transmitting station. The
galvanometer is placed at the place where the indications are to be made known and
his place I shall hereinafter refer to as the receiving station. The battery is
017

page_text: preferably placed at the receiving station. It will now be seen that the electric
circuit is complete and that a current flows through the galvanometer producing a
certain deflection of the needle. Let us now assume that the temperature at the
transmitting station rises. The mercury will rise further up the tube and the
amount of the high resistance wire a which is not immersed will be less so that
the resistance of the circuit will be roduced. This as is well known will cause an
increase of the electric current flowing through the galvanometer so that the needle
will be further deflected. If now the temperature should fall, the mercury will
sink in the thermometer tube, less of the wire a¹ will be immersed a longer length
of it will be traversed by the electric current and the resistance of the circuit will
be increased. Less current will now traverso the galvanometer and the needle being
deflected to a less extent a lower reading will be given. It will thus be seen that
the position of the needle on the scale of the galvanometer will vary with the
temperature at the transmitting station. If the galvanometer be an ammeter or
and
current measurer then readings will be in ampères fractions thereof and the
ог
constant of the apparatus being known or determined the temperature at the
transmitting station can be calculated from the current as shown by the galvano-
meter. The constant of the instrument being known however the galvanometer can
when desired be calibrated in terms of temperature so that the temperature at the
transmitting station can be read off directly on the galvanometer.
In
Figure 2 illustrates a more sensitive apparatus than that shown in figure 1.
this case the transmitting instrument D instead of being an ordinary mercury
thermometer as in figure 1 consists of a U shaped tube having a bulb at one end,
the other end being open or loosely stoppered. The U tube contains mercury as
shown and the bulb contains air or any other convenient gas. a¹ is the high
resistance wire which dips into the mercury as does the straight wire in the trans-
mitting instrument shown in figure 1. The reason why I use a spirally wound
wire in this case instead of a straight wire as in the former case is to assist in
rendering the instrument more sensitive, for it will be seen that owing to the
spiral form of the wire a given rise of the mercury will cause a much greater
length of wire to be immersed than if the wire were straight. The action of the
apparatus shown in this figure is the same as that of the apparatus shown in the
former figure except that instead of depending upon the direct expansion and
contraction of the mercury it depends upon the expansion and contraction of the air
in the bulb. When the air in the bulb expands with rise of temperature it forces the
mercury up the open limb of the U tube so as to cover more of the wire a' and lower
the resistance of the circuit. When the air in the bulb contracts with fall of
temperature the level of the mercury in the open limb of the U tube sinks and so
leaves more of the wire a¹ uncovered and thus increases the resistance of the
circuit.
Figure 3 shows an apparatus similar to that shown in figure 2 except that the bulb
instead of being at the top of the closed limb of the U tube is at the end of a pipe
or tube as shown. The form shown in figure 2 is adapted more especially for use
when it is the temperature of the air at a particular place which it is desired
should be made known, as for example the temperature of a room. Figure 3 is a
form more especially applicable for indicating the temperatures of masses of solids
as for example of a grain cargo. In this case the bulb is at the end of a long and
strong pipe and preferably of iron with a pointed end so that it can be forced down-
wards into the grain. When the pipe is of metal as in the case illustrated I prefer
that, except at the end where it is expanded to constitute the bulb, the bore of
the tube should be very small and I also prefer to divide the pipe into lengths separated
from one another as shown at ttt by pieces of non-conducting material so as to
prevent the transmission of heat along the pipe to the air in the bulb from a part
which may be at a higher temperature or vice versa the transmission of heat from the
bulb towards the other extremity of the pipe with a consequent reduction of tempera-
ture, and of expansion, of the air in the bulb.

page_text: In figure 4 I show another type of transmitting instrument. E is a strong box
with a flexible diaphragm or cover, say of thin corrugated metal e to which is affixed
the metal plunger F pressing upon the column of carbon discs G, G. superposed one
on another in the non-conducting tube H. J is a metal cover for the tube H. The
leads to and w³ are attached respectively to the plunger and to the cover.
with any convenient expansible fluid such for example as air.
E is filled
The action of this form of transmitting instrument depends upon the expansion an
contraction of the fluid in E under rise and fall of temperature. As the fluid in E
expands it forces the plunger F upwards so as to compress the carbon discs and
so lower the resistance of the circuit. As the fluid in E contracts the plunger falls,
the carbon discs are pressed less tightly together and the electrical resistance of
the current is increased.
The apparatus at the receiving station is the same in all the cases illustrated
and the action of the transmitting instrument produces the same effect in each
case, namely a reduction of resistance with rise of temperature, and increase of
resistance with fall of temperature. Of course it would be easy to arrange the
apparatus so that rise of temperature would produce increase of resistance and vice
versú, fall of temperature produce decrease of resistance as for example by inserting
the wire a in the other limb of the U tube from that shown in figures 2 and 3. In
such case it will of course be understood that the direction of the scale of the
galvanometer would be reversed, that is to say the needle would be deflected in
the opposite direction with riso of temperature to that in the cases illustrated in
the drawings.
I generally place a switch in the circuit close to the galvanometer so that the circuit
need be closed only when an indication or reading is desired.
I have hereinbefore mentioned the use of my apparatus in connection with a grain
cargo. In this case it is as a rule only necessary to know.the temperature when the
latter becomes sufficienty high to cause danger of over heating of the grain. So
long as the temperature remains below this point no reading is desired. In such a
case I prefer to place the wire a¹ in such position with regard to the level of the
mercury that the latter will not come into contact with the wire until the temperature
has been attained at which it is desired that the readings should commence.
same result can be obtained in the case shown in figure 4 by so adjusting the position
of the plunger F with respect to the cover J that the uppermost disc shall not come
into contact with the cover till the temperature at which readings are desired to
commence shall have been attained.
The
A corresponding case is when it is only necessary that readings should commence
when the temperature is low. Every Electrician will understand how to modify the
apparatus illustrated for this purpose. For example he would naturally arrange the
contacts as in an ordinary frost or low temperature aların: and in the case of
figure 4 he would reverse the tube H and its parts so that when the fluid in E
contracted it would bring the plunger into contact with the carbon discs and then in
its continued downward movement would compress the discs against J, it being
understood that J would now be the bottom of the tube H, and that continued
contraction would cause the plunger (suitably connected with the diaphragm) to press
the discs more and more against the said bottom J.
I have only specified a few of the forms of apparatus by which my invention may
be performed. Other forms which are obvious equivalents and which would not
depart from the principle of my invention will naturally occur to the mind of any
competent electrician. For example expansion and contraction as aforesaid might
be employed to vary the resistance of the circuit by bringing a larger or smaller
number of battery cells into circuit in series. In such a case a galvanometer con-
structed as a voltmeter and calibrated in volts degrees of temperature would be
a suitable receiving or indicating instrument.
and
ог
I frequently find it convenient to construct my indicating or receiving instrument,
that is to say the galvanometer, with two concentric or parallel scales, the one

page_text: calibrated in degress of temperature and the other in ampères or volts as the case
may be.
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 :-
1. The new or improved apparatus for enabling temperatures to be ascertained at
a distance substantially as set forth that is to say, apparatus by which alterations of
volume, or pressure, of an expansible fluid, produced by alterations of temperature,
at the transmitting station, cause alterations of the resistance of an electric circuit,
the said alterations of resistance causing alterations of the position of the needle of a
galvanometer at the receiving station, so as to indicate the temperature at the
transmitting station.
2. The combination of a transmitting instrument, a galvanometer and a source or
reservoir of electrical energy substantially as set forth.
3. The respective forms of transmitting instrument substantially as set forth with
reference to figures 1, 2, 3 and 4.
Dated this 23rd day of September 1889.
J. G. LORRAIN.