Improvements in and Connected with Thermometers.
Year: 1888

page_text: Date of Application, 12th Oct., 1888.
Complete Specification Left, 12th Aug., 1889-Accepted, 14th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in and Connected with Thermometers.
We, ROBERT FREE of The Elms, Mistley, near Manningtree in the County of
Essex, Maltster, and HENRY JAMES PIERCE of 24 Oaklands Grove, Uxbridge Road,
Shepherds Bush in the County of Middlesex, Engineer, do hereby declare the nature
of this invention to be as follows:-
The invention has for its object improvements in and connected with thermometers
whereby they may be adjusted to any desired degrees of temperature and caused to
sound a hell or other alarm or to operate a visible signal or signals whenever any
previously determined high or low temperatures are reached, and the invention is
intended more particularly for use where it is desired, in the process of drying malt
or other produce, to keep the temperature of the same within certain limits."
In
In carrying the invention into effect we employ two glass mercury tubes connected
to, and communicating with, the interior of a glass bulb, to which is connected a
glass tube or cylinder rising a short distance above and enclosing and protecting the
two mercury tubes. The glass bulb and tubes are enclosed within an outer protecting
metal tube or case, which is perforated at its lower part to permit the temperature of
the material under treatment to have free access to the outer glass tube and bulb.
the bottom of the bulb is fused a platinum contact stud, the upper end of which is
immersed in the mercury in the bulb whilst the lower end rests upon a spring contact
plate in connection with the metal case, thus forming an expansion contact which will
prevent injury to the glass tubes. The upper ends of the mercury tubes are closed
by rubber or other washers or valves, through which adjustable contact rods tipped
with platinum are passed; a rubber or other washer placed on the edge of the outer
glass tube and an insulating cap is placed over the same, which latter presses all the
washers firmly down on to the tops of the various tubes; tho adjustable contact rods
pass through the said cap and washers or valves and are capable of being raised or
lowered so that their lower ends may stand at the divisions on the scale representing
the limits of temperature at which it is desired to work.
A convenient way of fixing the insulating cap is to form the outer metal case in two
parts, the upper of which is formed with a short socket to fit over the lower, the upper
portion of the case rests upon the insulating cap and is forced downwards until the
desired compression of the washers is obtained; then two screws are passed through
lower portion of case to fix the insulating cap thereto, and other screws are passed
through corresponding holes in the two parts of the casing and into the insulating
cap, whereby all the parts are securely connected together.
The insulating cap is fitted with partially split metal contact tubes, through.which
the adjustable contact rods are passed and such rods fit tightly the unsplit portion of
the contact tubes, which latter are connected each to a terminal plate; one of such
terminal plates is connected by a conducting wire with a relay circuit and the other
to the bell circuit direct, whilst the case is connected with the relay circuit. Wo
preferably provide the case with a tripod stand by which it may be supported in an
upright position in the produce under treatment. The upper portion of the case is
formed with openings through which access is obtained to the adjustable contact rods,
and the lower portion of the case is provided with openings to enable the ends of the
adjustable contact rods to be seen.
By this arrangement of parts, when the mercury in one of the tubes rises into
contact with the adjustable contact rod set for the high limit of temperature, the high
toned bell circuit is closed and a bell is caused to ring or other audible or visible
indication is given, and when the mercury in the other tube falls below the end of the

page_text: sliding contact rod set for the low, limit of temperature, contact will be broken, which
will allow the relay armature to join contact and close the bell circuit and cause a
bell to ring or give other audible or visible indication; and these indications will
continue-until the temperature of the produce is again brought within the desired
limits.
TX
1000
ROBERT FREE.
HENRY JAMES PIERCE.
By Harris & Mills,
23, Southampton Buildings, Agents.
COMPLETE SPECIFICATION.
Improvements in and Connected with Thermometers.
We ROBERT FREE of the Elms, Mistley near Manningtree in the County of
Essex Maltster and HENRY JAMES PIERCE of 24 Oaklands Grove, Uxbridge Road
Shepherd's Bush in the County of Essex 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, reference being bad to
the accompanying drawings and to the Figures and letters marked thereon:
The invention has for its object improvements in and connected with thermometers
whereby they may be adjusted to any desired degrees of temperaturo and caused to
sound a bell or other alarm or to operate a visible signal or signals whenever any
previously determined high or low temperatures are reached and the invention is
intended more particularly for use where. it is desired in the process of drying malt
or other produce to keep the temperature of the same within any previously determined
limits.
Figure 1. is a vertical section and
Figure 2. is an elevation of a thermometer constructed according to our invention.
Figure 3. is a sectional plan drawn on the line 1. 1. of figure 1.
Figure 4. is a cross section drawn on the line 2. 2. of Figure 1.
Figure 5. is a cross section drawn on the line 3. 3. of Figure 1.
Figure 6. is a sectional plan drawn on the line 4. 4. of figure 1.
Figure 7. is an elevation of split contact tube and plate and Figure 8 is a diagram
representing the relay and bell circuits connected with the thermometer.
In all the Figures like parts are indicated by similar letters of reference.
a a are two glass mercury tubes connected to and communicating with the interior
of a glass bulb a to which is connected a glass tube or cylinder a rising a short
distance above and enclosing and protecting the two mercury tubes a.. a*. The glass
bulb a', and tubes a. a* a² are enclosed within an outer protecting metal tube or
case 5. 61 which is perforated at its lower part as shown, or in any other convenient
manner to permit the temperature of the material under treatment to have free access
.to the bulb a' and outer glass tube a². In the bottom of the bulb is fused a platinum
contact stud c the upper end of which is immersed in the mercury in the bulb a¹
whilst the lower end rests upon a spring contact plate d in connection with the metal
case b. thus forming an expansion contact which will prevent injury to the glass
tubes.
"
The upper ends of the mercury tubes a. a are closed by india rubber or other
washers or valves e e through which adjustable contact rods f. f* tipped with platinum
are passed, an india rubber or other washer g is placed on the edge of the outer glass
tube à and an insulating cap h is placed over the same which latter presses all the
washers ee and g firmly down on to the tops of the various tubes. a a* and a²; the
adjustable contact rods, f.. * pass through the said cap. and washers or valves e, e
and are capable of being raised or lowered so that their lower ends may stand at the
divisions on the scale representing the limits of temperature at which it is desired to
work.

page_text: A convenient way of fixing the insulating cap h is to form the outer metal case b. 61
in two parts the upper part of which is formed with a short socket to fit over the
lower part the insulating cap is forced downwards into the upper end of the
part of the case until the desired compression of the washers or valves e. e. and g
is obtained, then two screws are passed through the lower portion b of case to fix the
insulating cap thereto; the upper portion b' of the case is then placed in position
over the lower and other screws are passed through corresponding holes in the two
parts b. b of the case and into the insulating cap h whereby all the parts are securely
connected together.
1
The insulating cap his fitted with partially split metal contact tubes i i through
which the adjustable contact rods f. f* are passed and such rods fit the unsplit portion
of the contact tubes ii but the lower split portions of such tubes being sprung
inwards will put friction on such rods and thereby assist to hold them in any given
position whilst they will also secure metallic contact with the rods f. f* in the event
of any wear taking place. The contact tubes ii are connected each to a terminal
plate one of which is connected by a conducting wire with a relay circuit and the
other by a wire is to the bell circuit direct whilst the case b. b is connected by cou-
ducting wires 6, 6 with both the relay and bell circuits. The upper portion 6 of the
case is formed with openings 6° 6 through which access is obtained to the adjustable
contact rods ff* and the lower portion 6 of the case is provided with openings 6 to
enable the lower ends of the adjustable contact rods to be seen. We preferably provide.
the case with a tripod stand by which it may be supported in an upright position in
the produce under treatment and with a hook 6 by which it may be hung up when
not in use.
Thus the attendant can by means of the openings in the upper portion b₁ of
the case obtain access to the adjustable contact rods f. f* and thereby adjust their
lower ends to any desired limits of temperature. A sliding cover is employed to
cover the openings when access is not required to be had to the contact rods f. f*.
We will now by reference to the diagram Figure 8 describe the action of the
apparatus when any previously determined degree of high or low temperature is
exceeded.
k is the relay battery, one terminal of which is connected by the wire with the
low temperature contact rod f whilst the other terminal is connected by wire 68 with
one terminal of the coils of an electro magnet whose other terminal is connected by
the wire with the case of the instrument. Thus so long as the contact is maintained
between the mercury and the rod f of the low temperature tube a the relay circuit
is closed and the armature m is attracted to the electro magnet but when such
contact and circuit are broken by the falling of the mercury in the tube a the
armature m falls away from the electro magnet and its free end then dips into a
mercury contact cup n which by a wire n' is connected with one terminal of the bell
battery o whilst the hinged end of the armature m is by wire m¹ connected with the
electric bell p which latter is also by a wire p¹ connected with the opposite terminal
of the bell battery o this will cause the low temperature bell p to ring until by a rise
in the temperature of the produce under treatment the mercury again rises into
contact with the low temperature rod f which by closing the relay circuit causes
the armature m again to rise out of contact with the mercury cup n and thereby
breaks the bell circuit and so stops the ringing of the bell p. The high temperature
contact rod f* is by a wire connected to one terminal of the bell battery o whilst
the case b. b¹ is connected by wire &* with the high temperature bell wbich latter
is also connected by wire with the opposite terminal of the bell battery o.
Thus when by an increase of temperature in the produce under treatment the
mercury in the high temperature tube a* rises into contact with the contact rod f
the bell circuit is closed and the high temperature bell q caused to ring until the
temperature of the produce under treatment is so reduced as to break the contact
between the mercury and contact rod f* in the high temperature tube a*.
If desired a visible indication may be used in lieu of or in addition to a bell or other
audible signal.

page_text: We would here remark that the method of wiring the thermometer to the bell and
relay circuits may be variously modified so long as they are caused to operate in the
manner, hereinbefore described.
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 improved construction of adjustable signalling or indicating thermometer
substantially as herein shown and described and for the purpose stated..
2. In connection with adjustable signalling or indicating thermometers for high and
low temperatures the combination therewith of relay and bell or sign indicating
circuits substantially as herein shown and described and for the purpose stated.
Dated this 10th d
1000
ROBERT FREE..
HENRY JAMES PIERCE.
By Harris & Mills,
23, Southampton Buildings, London, Agents.