An Improved Universal Thermometer.
Year: 1892

page_text: Date of Application, 7th July, 1892-Accepted, 8th Oct., 1892
COMPLETE SPECIFICATION.
[Communicated from abroad by HANS HARTL, of Reichenberg, Bohemia,
Professor.]
An Improved Universal Thermometer.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35 Southampton Buildings, Chancery Lane, in the County of
Middlesex, 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:―
This invention relates to improvements in universal thermometers and the object of
the improvements is to provide means which will permit
1) to read off directly the temperature indicated by the thermometer,
2) to announce or indicate continually this indicated temperature to a distant
room or station,
3) to adjust the thermometer for any temperature so that a rising or falling
of the mercury for 1-2° C. is also indicated at a distant station.
a
"
The improved thermometer (illustrated in Figure 1 of the accompanying
drawing) consists of two closed bulbs or cisterns "a and b," connected with each
other by a flexible tube "G." Into the cistern "a" are fastened by melting-in,
the platinum-wires "1 and 3," and into the cistern "6" the platinum-wire "2."
To a cover cemented air-tight on the cistern "6" is fixed a small carbon
block "K," against the hollowed lower side of which presses by means of buoyancy
a carbon-bar" floating in the mercury. The quantity of the mercury (shown
in black in the figures) is to be measured in such a manner that when it is in "
(for instance) a short distance from the platinum-wire "1," it is in "6" at the
same distance below the platinum-wire "2." The leg of the cistern or bulb "b"
is firmly fixed to the base-plate of the instrument, whilst the leg of the bulb "
is mounted on a sliding-piece "s" sliding in a guide-groove in the base-plate. The
moving of the sliding-piece "s" may be effected by turning a pulley "R," to which
the sliding-piece "s" is suspended by means of a string or chain "." The
spring-catch or pawl "j" gearing with a ratchet-wheel firmly secured upon the
pulley "R," locks the sliding-piece "s "in any desired position.
upon
"
a
"
The platinum-wires "1 and 3" are connected with the springs "x and y," which
slide the metal-wires 66
Im and n so as to form an electrical contact.
Above the mercury are saturated vapours of different liquids, for instance,
in a
66
"such as ether, in "&" alcohol (or alcohol in "al" and water in ""). The
tensions or pressures of these vapours differ from each other. The difference of
pressure of the said vapours is the higher, the higher the temperature rises. This
difference of pressure is utilized for moving the mercury and thereby effecting an
indication of the temperature. The additional pressure existing in "
"" to "b,"
increasing with the rising of the temperature drives the mercury from "a
which of course, will rise with the rising temperature. Without interfering with
the nature of the invention the cistern". a may be filled with steam, and the
cistern "6" with atmospheric air, or air may be used for both cisterns but of
different density.
"
a
"
and
When the sliding-piece "s " is in its lowest position, that is to say resting upon
the stop "u" of the base-plate, the height of the mercury in the tube "b," i.e. the
reading of the thermometer, indicates directly the temperature upon a thermometric
scale arranged close by the said tubular leg "b."
When the temperature is to be maintained at a given distinct height, for
instance at 40° C., the sliding-piece must be lifted or raised so high that the

page_text: current.
65 33
3:
as the
spring points to the division-line marked by "40" of another scale fitted
beside the wire « m." This adjustment corresponds to the position of the
thermometer, in which at 40° C. the mercury in both legs is at an equal distance
below the platinum-wires "1 and 2." As soon as the temperature increases
by 1-2° C. the mercury reaches the platinum-wire "2," and as soon
temperature decreases, the mercury will reach the platinum-wire "1," whereby
the platinum-wire "2" or "1" is electrically connected with the wire "3," so
that a signalling device at a distant station may be actuated by an electrical
The signal device consists of a sounder L and a moveable pointer or
hand "carrying a small permanent magnet ns," which swings under a tripolar
electro-magnet "N. S. N." The free poles of the Leclanché-elements "E I and
E 2" coupled or joined up in series, are connected with the platinum-wires "}
and 2," whilst a conducting wire leads from the jointed poles through the
sounder "L" and the induction-coil of the electro-magnet "N. S. N." to the
platinum-wire "3." The course of the circuit is shown in the figures by pointed
and dotted lines.
66
66
>>
If now in the above supposed instance the temperature rises to 42°, the circuit
between 3 and 2" is closed. The bell of the signal device will therefore sound,
whilst the pointer "i" being deflected to the right hand points to "hot." But
if the temperature sinks to 38° C. the circuit between "3 and 1" is closed, and
the sounder rings again, but the pointer "i" on account of the changed direction
of the current points to the left hand, to "cold."
For continually indicating the temperature at a distant station, the sliding
piece S "is brought to its lowest position and the commutator "P," the metal-
parts of which are shewn in sectional lines in Figure 1, is turned as far as to touch
the small pin or stud "o." Then the circuit, represented by the dotted lines only,
is closed. The current leads from "E 2" to the metal-wire ". n" and, branching
there, continues its way. One of the branches leads through the nickel-coil "I
to a terminal "c," the other passes from "3" through the mercury and the carbon-
bar to the carbon-block "K," and from there to the terminal "d." With the
rising temperature the mercury in the leg "" also rises. But thereby the pressure
of the carbon-bar against the carbon-block also increases, so that the intermediate
resistance is diminished.
"e" and "d" are junctions of a Wheatstone bridge. On the semi-circular
measuring-wire of the latter there slides a pointer "Z," which by connecting
the above mentioned branch-circuits leads the current to the contact "g" of
the lever "h," and from there through the selfacting interruptor "U" back to the
battery. The contact "g" is not closed, except when the telephone "T," the
terminals of which are connected with "c and d," is taken off from the bearing-
lever "." The measuring-wire is divided by the hand or pointer "Z" into the
parts "cf" and "df," and according to the laws of Wheatstone's bridge no current
will pass through the (taken off') telephone, if the resistances of the branch-circuits
described are in due proportion to the resistances of the parts "cf" and "df" of
the measuring-wire. Since with the rising temperature the intermediate resistance
between "v and K" diminishes, whilst the resistance of the nickel resistance-coil
increases, any temperature must correspond to a quite distinct adjustment of the
pointer "Z," at which the telephone is without current and "humming" will not
be heard in it.
The method of reading off the temperature is as follows:
The telephone is held to the ear and the pointer "Z" turned till the humming in
the telephone ceases. As soon as this happens, the pointer "Z" indicates the
temperature of the thermometer on a scale arranged close by the measuring-
wire.
"
In Figure 2 is shown a mechanical arrangement for continually indicating the
temperature at a distant station. The pulley "R" carrying the sliding-piece ".
is connected by a cord or chain "1" with the shaft "W," arranged in the room
8

page_text: or place where the temperature is to be indicated. From the element "E" the
conducting-wire leads through the signaling device "L" to the wire "n," and
from the other pole of the element to the platinum-wire "2." If the shaft "W"
is now turned in a direction contrary to that of a watch-hand, the pulley "R" will
be turned also in the same direction, thereby raising the sliding-piece "s," until the
mercury touches the platinum-wire "2." At this moment the circuit is closed and
the signal sounds. The tapering end of the crank-lever or handle of the shaft "W"
then indicates the temperature of the thermometer on a scale arranged round
the shaft "W."
The thermometer shown by Fig. 3 depends upon the same theoretical conditions,
but differs from the thermometer already explained only by the transposition of
the contacts. The thermometrical tube "G" bent as shown is fastened by the
means of the arm or rod "H" to the metal-block "K," which turns on a knife-
edge "o." The block "K" is provided with a pointer "Z," which directly
indicates the temperature on a special scale. The pressure of the vapours
contained in "a," growing higher with the rising of the temperature, drives up
the mercury in "," so that the centre of gravity is altered and shifted to the
right hand. Hereby the whole apparatus and consequently also the pointer are
turned to the right hand, whilst by the falling temperature a turning to the left
hand is effected.
"
The pointer "Z" is provided with a platinum-pin "p," which according to the
position of the pointer "Z" will come into contact with one of the small platinum-
plates 1 or 2," mounted on slides "a and y," which are electrically connected
with the wires " m and " by means of springs sliding upon the said wires. The
wires " and n
m
are enclosed in an arch-shaped piece of ebonite or vulcanite "F,"
having a trapezium-like cross-section terminating in terminals. The sides "
and y" moveable on the arch-shaped vulcanite, are furnished with pointers extending
to the scale (Fig. 3).
"
"
"
Supposing the temperature of a room is to be maintained between 38 and 40
degrees C., the slides must be adjusted so that their pointers point to "38
or "40"
respectively. As soon as one of these temperatures is reached, the platinum-
pin "pcoming into contact with "1 or 2" closes the circuit, whereby the
indicating mechanism "A" (Fig. 3) is put into action. This indicating mechanism
and also the path of the current are similar to those shown by Fig. 1.
t
For continually indicating the temperature at a distant station, there are
arranged in the base-plates above the scale a number of small metal-plates
separated from each other by small intervals, but connected with each other by
thin wires. The pointer "Z" is bifurcated at its outer end. The width of this
bifurcation is greater than the intervals between the above mentioned small
metal-plates so that always at least one branch of this bifurcation is in contact
with one of the small metal-plates, the first and the last of which are connected
with the junctions "e and d" of a Wheatstone bridge by means of conducting
wires. The conducting or supplying of the current is effected by means of the
pointer "Z." The position of the conducting wires corresponds to that shown
by dotted lines in Fig. 1. The whole system of the small metal-plates and
connecting-wires forms a conductor of a considerable resistance. This conductor
is divided by the bifucated pointer into two parts, the resistances of which
determine the proportion of the resistances in the branch-circuits "C and D."
If the galvanoscope "M" placed in the circuit between "cand d" is to point to
zero, the slide "f" sliding on the measuring-wire "cd" must be adjusted so that
the parts "cf" and "d f" are proportional to the resistances of the said branch-
circuits. Since these resistances depend upon the position of the pointer ","
i.e. upon the temperature, hence it follows, that a distinct adjustment or position
of the slide "/ for the bridge without current corresponds to a determined
temperature.
"
The reading off of the temperature takes place in the following manner: The
slide "" is to be moved till the galvanoscope "M" points to zero; then the hand

page_text: of the slide "" indicates directly the temperature upon the scale relating to the
said slide.
Figure 3 shows a modified method of indicating the temperature at a distant
station. In this arrangement each metal-plate of the thermometer is connected
with a corresponding metal-plate of the indicating apparatus by means of suitable
conducting-wires. The metal-plates, being arranged in the form of an arch, are
insulated from each other and are marked with numbers corresponding to the
respective degrees of temperature. A metal-pointer "i" when turned round will
come successively into contact with the metal-plates. The circuit of the current
appears from the figure. If the temperature of the thermometer is to be ascertained,
the pointer "" must be turned until the signal apparatus "L" sounds. The
metal-plate touched by the pointer then indicates the temperature.
The instruments shown by Figures 4, 5 and 6 are modifications of the
thermometer illustrated in Figures 1 and 2.
The thermometer shown by Figure 4 is suitable for continually indicating the
temperature at a distant station. The arrangement is in this case a symmetrical
one. In both legs or cisterns of the thermometer there are carbon bars pressing
against carbon blocks. The current enters through the platinum-wire "3" whilst
it leaves at "m and n and is led to the junctions of a Wheatstone bridge in the
same manner as in Fig. 1.
"
In the modification shown in Fig. 5 both cisterns and their legs are equal to
each other and are mounted each upon a sliding piece "s
*
":
"
and " respectively.
The scale for the adjustment of any desired temperature is arranged around the
pulley R." If this temperature is a fixed one, as for instance in school-rooms,
hospitals, and the like, the sliding pieces "s and s 1," after being adjusted may be
fixed in their respective positions by any suitable means, as is indicated in the
arrangement shown by Fig. 6.
The spring-clamp or clip "q" (see Figs. 2, 4, and 6,) has a double purpose.
By screwing on the said clip tightly the liquids will be hindered from passing from
one cistern or leg into the other during transportation from place to place. By
screwing on the clip with a more or less amount of pressure the sensibility of the
apparatus may be regulated. Supposing the clip to be wholly loosened and the
thermometer shown by Fig. 6 adjusted so that at 17° C. the mercury in both legs
is about one fourth of an inch below the platinum-wires "1 and 2." If now the
clip is screwed up a little, the mercury in both tubes or legs will rise and be
brought nearer to the platinum-wires so that then a very slight alteration or
change of the temperature is sufficient to actuate the signal apparatus.
cr
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what 1
claim and desire to secure by Letters Patent, is :
1) An universal thermometer indicating the temperature by moving or displacing
the mercury contained in a bent, double-armed tube, which movement of the
mercury is effected by gases or vapours being enclosed in the upper ends of the
said tube or cistern above the mercury and having a different tension depending
on the temperature so that the gases or vapours will exert unequal pressures, the
difference of which causes a displacement of the mercury at any change or
alteration of the temperature.
2) In a thermometer characterized by Claim 1 the arrangement of conducting-
bars floating in the mercury-colums, which conducting bars are pressed with a
variable pressure against contacts placed in the circuit, the said pressure corre-
sponding to the buoyancy. varying with the varying height of the mercury colums,
thereby producing on an indicating apparatus alterations or changes of resistance
in the derived currents passing through the legs of the thermometer.
3) A thermometer such as characterized by Claim 1 whose mercury colums,
either by means of a movement or displacement of the legs of the tube to each
other according to the different temperatures to be indicated, or by means of a

page_text: distinct position of the legs to each other according to a fixed normal temperature,
receive such an adjustment of their heights, visible on a scale, that the additional
pressure between the gases produced by the temperature to be indicated raises one
or the other of the mercury colums so that by touching a contact a circuit is closed,
which will actuate a signalling and indicating apparatus.
4) A thermometer such as characterized by Claim 1 arranged as a pendulum-
thermometer so that a displacement of the mercury in the legs of the tube will cause
an inclination of the thermometer and also of a pointer connected thereto, which
pointer divides a conductor into two parts producing thereby changes or alterations
of resistance which can be transferred to an indicating apparatus.
TI 1902
EDWARDS & Co.,
Agents for the Applicant.