Electric Transmitting Thermometer.
Year: 1895

page_text: Date of Application, 14th Mar., 1895-Accepted, 24th May, 1895
Electric Transmitting Thermometer.
I, FRANCIS NAPIER DENISON, of 26, Denison Square, in the City of Toronto,
in the County of York, in the Province of Ontario, Canada, Electrician, 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:
My invention relates to improvements in thermometers, and the object of the
invention is to devise a thermometer in which the rise and fall of the temperature
will be communicated electrically to any desired point, and recorded at such point,
and it consists essentially of a thermometer the tube of which is provided throughout
the greater portion of its length with a manganese steel conducting wire, or other
suitable high resistance conductor, centrally located in the tube and having
conducting wires, one passing from the top of the high resistance wire through the
tube and the other connected to the bottom of the wire and passing out laterally
through the tube, the conducting wires and thermometer being encased and the
wires leading off to a suitable indicator preferably through a cable, which is used
to support the thermometer as hereinafter more particularly described.
The drawing represents a sectional perspective view of a thermometer constructed
in accordance with my invention, and intermediately broken away, the connections
to a suitable indicator being represented in diagram.
A is the glass tube, and A¹ the bulb of the thermometer which is provided with
mercury or other suitable conducting fluid usually employed in thermometers.
The tube A is practically encased in a cylinder B of rubber, fibre or other
insulating material, the bottom of which cylinder is provided with shoulders b
against which the upper part of the bulb is held, so as to strengthen it at the point
of junction with the tube. The solid cylinder B is enclosed in a suitable cylindrical
metal casing C which is externally threaded at the top c and at the bottom c¹ to
receive the top and bottom caps D and E respectively. Within the top D
I provide a block F of rubber, fibre or other insulating material, which is prevented
from moving vertically by the hemispherical top d of the cap.
The bottom cap E I preferably perforate, so as to permit of the free admission
of air, water or other liquids around the bulb A¹.
G is the central wire of manganese steel preferably extending from near the
bottom of the tube to near the top thereof, where it is connected to a platinum
wire which passes through the closed end into a screw plug g' screwed in the
centre of the top of the solid cylinder B. The bottom of the wire is bent, so as to
extend laterally into the side of the glass tube where it is connected to a heavier
wire ga preferably of platinum, which is fused in the glass and extends inwardly to
the mercury. The outer end of the platinum wire is connected to a heavy copper
or steel wire g³. The wire 93 passes through a notch b' made in the shoulder b,
which notch is filled with rubber, cement or insulating material, so as to completely
insulate such wire. The wire y³ passes up through a hole to a ring 9 let into the
top of the solid cylinder B.
His a metal plug fitting within a central hole F¹ made in the block F. ƒ is a
compression spring fitting between the plug and the upper end of the hole. The
bottom of the spring is secured in the top of the plug. The top of the spring is
connected by a wire i passing through a hole f¹ in the block F to one strand of the
cable 1. Jis a plug which fits within a hole F2 which is directly opposite the
ring g'. The plug J has a spring f2 fitting between it and the top of the hole,
the bottom of the spring extending into the plug. is a wire connected to the top

page_text: of the spring and extending through a hole f³ in the block F to the other strand of
the cable I. The lower ends of the strands of the cable I are wrapt around and in
between the strands by any suitable wrapping as shown so as to form a knot I
The top of the cap D has a hole d' formed in it through which the cable passes,
which hole is surrounded by an outwardly extending flange d'. The wrapping 12
is passed around the cable to the outside, as shown, so as to prevent any wear on
the cable at the edge of the hole d', and also to serve, together with the knot I, to
keep the interior of the cap D perfectly water tight. The knot I' also serves to
prevent any strain coming upon the wires i i.
I preferably provide the metal ring gas herein before described, in order that,
when the cap D is being screwed on to the casing C, the plug J will always
complete the connection to the wire g³ through such ring no matter how far the cap
may be screwed upon the cylindrical casing C.
The wires i, of the cable are carried to terminal posts K K¹ which are connected
to suitable electrical mechanism which actuates the pointer L in connection with
the scale M' of the indicator M. The indicator M is placed at any convenient
point and at any distance from the thermometer tube. A battery N or other
suitable generator of electricity is provided. Any suitable indicator may be used
and I do not at present lay claim to any specific form. The arrangement which
I prefer to use will form the subject-matter of a separate application.
The action of the thermometer is very simple and is as follows. Immediately,
upon the mercury or liquid in the thermometer rising, the resistance on the wire G
is decreased and the current is increased, thereby electrically causing a corre-
sponding rise in the scale M¹. When the mercury in the thermometer falls the
resistance is necessarily increased, and less current would pass, thereby causing the
pointer to fall.
My invention is particularly designed for marine work, as the form of the
thermometer is such that it might be thrown outside a vessel without injuring
the device, and the proximity of icebergs would be communicated to the indicator
or recorder which may be placed in the captain's cabin, on the bridge, or in any
other suitable convenient position. It may also be used in deep sea work, in
meteorological work, in the centre of grain bins, in elevators, in factories, and for
various purposes where the thermometer is placed at some inaccessible point as to
its reading, and where it is important that the various changes in temperature
should be communicated immediately.
When my thermometer is to be used for marine work it will be understood that
it must be of sufficient weight to drop substantially to the perpendicular. It may,
therefore, if necessary be weighted. Although I show the thermometer attached
to the end of a cable, so that it may be thrown overboard, it will be understood
that it might be enclosed by a suitable cage, preferably on the outside of the bow
of the vessel, beneath the water line. The wires in this case might be led through
the interior of such vessel.
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. In a thermometer, a tube having a central wire or conductor of more or less
resistance passing through it, and electrical means connected at the ends of such
wire for recording the change in temperature as the mercury or other liquid
expands or contracts, as and for the purpose specified.
2. In a thermometer, a tube having a central wire or conductor of more or less
resistance passing through it, an insulating casing for the tube, a platinum wire
connected to the top of the high resistance wire in the tube and leading through
the insulating casing, a platinum wire connected to the lower end of the central
wire within the glass tube, and a conducting wire leading therefrom, and leads from
the ends of both conducting wires to an electrical indicator, as and for the purpose
specified.

page_text: 3. The combination with the mercury tube and bulb held centrally in a suitable
solid cylinder of insulating material, of a metal casing surrounding such cylinder, a
central high resistance wire extending through the major portion of the tube, a wire
extending through the upper end of the tube to a screw plug, a heavy wire
extending laterally from the lower end of the high resistance wire through the
insulating cylinder and vertically to a ring let into the top of the cylinder, a cap
screwed on top of the cylindrical casing, an insulating block securely held from
vertical movement within the cap a central hole and a plug held in contact with
the screw plug in the top of the insulating cylinder by a spring connected to the
metal plug at the top, a hole made in the block opposite to the ring on the top of
the cylinder, a metal plug held in frictional contact with such ring on the top of
the cylinder by a suitable spring within the hole, and wire leads to the indicator, as
and for the purpose specified.
4. The combination with the tube and bulb held centrally in a suitable solid
cylinder of insulating material, of a metal casing surrounding such cylinder, a
central high resistance wire extending through the major portion of the tube, a
platinum wire extending through the upper end of the tube into a screw plug,
a heavy wire extending laterally from the lower end of the high resistance wire
through the insulating cylinder, and vertically to a ring let into the top of the
cylinder a cap screwed on top of the cylindrical casing, an insulating block securely
held from vertical movement within the cap a central hole and a plug held in
contact with the screw plug in the top of the insulating cylinder by a spring
connected to the metal plug at the bottom, a hole made in the plug opposite to the
ring on the top of the cylinder, a metal plug held in frictional contact with such
ring on the top of the cylinder by a suitable spring within the hole, wire leads to
the indicator, a cable containing the lead wires and passing through a hole in
the top of the cap and a knot formed within the hole, as and for the purpose
specified.
5. The combination with the tube and bulb held centrally in a suitable solid
cylinder of insulating material, of a metal casing surrounding such cylinder, a
central high resistance wire extending through the major portion of the tube, a
platinum wire extending through the upper end of the tube into a screw plug,
a heavy wire extending laterally from the lower end of the high resistance wire
through the insulating cylinder and vertically to a ring let into the top of the
cylinder, a cap screwed on top of the cylindrical casing, an insulating block
securely held from vertical movement within the cap, a central hole, a plug held in
contact with the screw plug in the top of the insulating cylinder by a spring
connected to the metal plug at the top, a hole made in the block opposite to the
ring on the top of the cylinder, a metal plug held in frictional contact with such
ring on the top of the cylinder by a suitable spring within the hole, wire leads to
the indicator, a cable containing the lead wires passing through a hole in the top
of the cap and a wrapping passed around the cable to the outside of the hole, as
and for the purpose specified.
6. The combination with the tube and bulb insulated and supported in a suitable
casing, as specified, and a high resistance wire passing through the major portion
of the tube and connected to suitable leads, of a cable which forms a support for
the thermometer casing, as and for the purpose specified.
7. The combination with the tube and bulb insulated and supported in a suitable
casing, as specified, and a high resistance wire passing through the major portion
of the tube and connected by suitable leads to the cable, which forms the support
of the thermometer casing, of a perforated cap secured to the lower portion of the
casing and partially surrounding the bulb, as and for the purpose specified.
Dated the 14th dow of March 190:
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.