IMPROVEMENTS IN THERMOMETRIC APPARATUS
Year: 1885

page_text: I ALFRED GEORGE BROOKES of the firm of W Brookes & Son of 55 & 50
Chancery Lane in the County of Middlesex Patent Agent do hereby declare tho
nature of my invention for IMPROVEMENTS IN THERMOMETRIC APPARATUS to be
as follows:
This invention relates to thermometers or thermometric apparatus in which the
pointer is moved by the expansion or contraction of a solid material, usually a
lamina or strip composed of two metals of unequal expansibility which twist or
become distorted under change of temperature.
The main object is to simplify and cheapen the construction of and thus enable
thermometers of the class referred to, to be made of superior quality and at much
less expense than those heretofore produced.
The sensitive portion of the thermometer or that which actuates the pointer
when the temperature changes, consists of a helical coil composed of two strips of
material usually iron or steel, and brass, which have different rates of expansion
thus causing the coil to curl or twist around as the temperature varies, one end of
the sensitive helical coil being made fast while the other end is connected through.
suitable mechanism with the pointer.
Also the combination with a sensitive helical coil and pointer, of connecting
mechanism between them, whereby said sensitive coil may be arranged with its
axis at right angles to that of the pointer thus economizing space in the instru-
ment, the connecting mechanism also serving to multiply or magnify at the pointer
the movement produced by the said coil.
Also in a holding device, for the fixed end of the helical coil whereby the
position of the point of attachment of one end of said coil with the holding device
may be varied; or whereby the effective length of the said coil may be adjusted,
so that the sensitive helical coils of a number of instruments may be made to
produce the same amount of movement of the pointer under like change in
temperature, although the said helical coils are themselves not exactly uniform
owing to difference in size. This adjustment enables the dials, pointers, and other
.
077

page_text: parts of the mechanism to be readily set to operate uniformly under like conditions
thus enabling the production of helical coils in quantity and insuring a high
quality of work at a comparatively moderate expense.
Also an adjusting device for varying the position of the helical coil with
relation to other parts of the mechanism so that the pointer may readily be set at
the proper graduation on the dial for a given temperature.
Also in providing secondary or registering pointers which are moved by the
main pointer, one in the one and the other in the other direction, accompanying
the pointer in its maximum movement in either direction but remaining stationary
during the return movement of the main pointer, so as to indicate at the end
of any period of time the maximum movements of the main pointer in both
directions; or in other words to indicate the highest and lowest temperature to
which the instrument has been exposed during the said period of time.
The said registering or maximum and minimum pointers cooperate with a
secondary dial or series of graduations preferably of smaller diameter than that
which cooperates with the main pointer, and the secondary pointers are smaller
than the main pointer so that there is no danger of mistaking the one for the
other.
According to the invention the temperature is indicated on a graduated dial by
means of a main pointer connected with an arbor provided with a pinion, meshing
with a toothed segment having an arm connected with one end of the sensitive
helical coil, the other end of which is made fast or held stationary by an attaching
device, connected with an upright extended from a plate, constituting the frame-
work for the sensitive helical coil and the connecting mechanism between it and
the pointer, the said plate being attached to the dial, plate in any suitable manner
as by screws.
The axis of the toothed segment is in line with the axis of the sensitive helical
coil, which is at right angles to the axis of the pointer, so that the coil so formed
lies parallel with the dial plate thus economizing space and making a more
convenient instrument than those heretofore made in which the axis of the
sensitive coil is in line or parallel with that of the pointer so that the said coil
projects lengthwise from the dial plate.
The ends of the arbor of the segment are pointed to form pivots and the steps or
bearings for said pivots are both adjustable in the direction of the axis of the
arbor, the said steps in this instance being made as screws supported in projections
of a bridge connected with the plate, the said bridge also constituting a bearing
for one end of the arbor.
By making the steps adjustable the toothed segment may be readily set to
mesh properly with the pinion, a matter which would otherwise be difficult to
accomplish.
The arm for supporting the fixed or stationary end of the sensitive helical coil is
provided with a clamping device, say a set screw for engaging one end of the said
coil, which may thus be made fast at any desired distance from its end in order to
vary the length of its effective portion between the said arm and the point of
attachment of the said coil to the toothed segment, thus the dials, pointers, and
connecting mechanism between the latter and the sensitive helical coil may all be
made uniform, so that if when assembled in the thermometer it should be found by
testing that the amount of movement is too great or too small for a given change
in temperature, the clamping device may be loosened and the sensitive helical coil
be taken up or let out, to shorten or lengthen as may be required the portion
between the points of attachment of the said coil, thus decreasing or increasing its
effect on the pointer until the proper adjustment has been secured.
f.
In order to set the pointer at the proper position on the dial after the adjust-
ment of the helical coil has been made, the arm is connected with a shaft turning
in the upright and provided with an arm engaged by an adjusting screw to produce
a minute or slow movement of said arm and connected arm, by which the entire
helical coil is moved bodily without changing the relative position of its attaching

page_text: points, and thus through the gear and pinion also moving the pointer until it is in
exactly the right position.
The shaft may be turned independently of the arm to bring the pointer nearly
into correct position, within the range of movement provided for by the screw,
after which the arm is made fast on the arbor by a set screw.
The entire instrument may be enclosed in a case composed of a ring, forming a
frame over the dial, preferably covered with glass, an a back plate provided with
an opening opposite the adjusting screw, the said opening having a removable cap
provided with projections, which pass through notches in the plate, and by a partial
turn engaging said plato, fastening the cap or cover in position to close the
opening, by removing the cap a screw driver may be inserted, and the screw
turned to adjust the position of the pointer after the instrument is put together
and encased.
The pointer which is moved by the sensitive helical coil to indicate changes in
temperature is provided with a. pin or projection cooperating with secondary or
registering pointers pivoted on a stationary bub or centrepiece surrounding the
pointer arbor the said registering pointers remaining stationary until moved by the
projection of the main pointer.
The one registering pointer is caused by the projection to accompany the main
pointer in its movement in one direction, and this registering pointer accompanies'
the main pointer in its movement in the other direction, each registering pointer
being carried by the main pointer as far as the latter moves in one or the other
direction, the secondary pointer remaining stationary on the return movement of
the main pointer so that the registering pointers will remain as left by the main
pointer thus indicating the maximum movement of the main pointer in either
direction.
In order that the indications of the registering pointers may not be confused
with the reading of the main pointer the said registering pointers are made shorter
or smaller than the main pointer, and cooperate with a secondary dial or series of,
graduations.
In order to relieve the sensitive helical coil composed of a bi-metallic strip from
lengthwise strain between its points of attachment, an arm is connected with the
a bor by a joint which permits said arm to rock slightly on that arbor to accommo-
date any movement of the end of the coil connected with the said arm in a
direction parallel with the axis of the said coil, without however permitting the
said end of the coil engaged by the clamping device to have any movement around
its axis.

page_text: Improvements in Thermometric Apparatus.
I ALFRED GEORGE BROOKES of the firm of Wm Brookes & Son of 55 & 56
Chancery Lane in the County of Middlesex Patent Agent, do hereby declare the
nature of my invention for IMPROVEMENTS IN THERMOMETRIC APPARATUS 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 thermometers or thermometric apparatus of that class
in which the pointer is moved by the expansion or contraction of a solid material,
usually a lamina or strip composed of two metals of unequal expansibility which
twist or become distorted under change of temperature.
The main object of this invention is to simplify and cheapen the construction of
and thus enable thermometers, of the class referred to, to be made of superior
quality and at much less expense than those heretofore produced.
In the invention herein to be described the sensitive portion of the thermometer
or that which actuates the pointer when the temperature changes, consists of a
helical coil composed of two strips of material usually iron or steel, and brass,
which have different rates of expansion thus causing the coil to curl or twist
around as the temperature varies, one end of the sensitive helical coil being made
fast while the other end is connected through suitable mechanism with the pointer.
A sensitive helical coil is well known in the arts and hence is not herein claimed
broadly.
The invention consists partly in the combination with a sensitive helical coil
and pointer, of connecting mechanism between them, substantially as hereinafter
described, whereby said sensitive coil may be arranged with its axis at right angles
to that of the pointer thus economizing space in the instrument, the conuecting
mechanism also serving to multiply or magnify at the pointer the movement
produced by the said coil..
The invention also consists in a holding device, substantially as herein described,
for the fixed end of the helical coil whereby the position of the point of attachment
of one end of said coil with the holding device may be varied; or whereby the
effective length of the said coil may be adjusted, so that the sensitive helical coils
of a number of instruments may be made to produce the same amount of movement
of the pointer under like change in temperature, although the said helical coils are
themselves not exactly uniform owing to difference in size. This adjustment
enables the dials, pointers, and other parts of the mechanism to be readily set to
operate uniformly under like conditions thus enabling the production of helical
coils in quantity and insuring a high quality of work at a comparatively moderate
expensc.
The invention also consists in an adjusting device for varying the position of
the helical coil with relation to other parts of the mechanisin so that the pointer
may readily be set at the proper graduation on the dial for a given temperature.
The invention also consists in various minor details of construction which will be
hereinafter more fully pointed out.

page_text: The invention also consists in providing secondary or registering pointers which
are moved by the main pointer, one in the one and the other in the other direction,
accompanying the pointer in its maximum movement in either direction but
remaining stationary during the return movement of the main pointer, so as to
indicate at the end of any period of time the maximum movements of the main
pointer in both directions; or in other words to indicate the highest and lowest
temperature to which the instrument has been exposed during the said period
of time.
The said registering or maximum and minimum pointers cooperate with a
secondary dial or series of graduations preferably of smaller diameter than that
which cooperates with the main pointer, and the secondary pointers are smaller
than the main pointer so that there is no danger of mistaking the one for the other.
Fig. 1 is a front elevation of a thermometer embodying this invention.
Fig. 2 a rear elevation of the sensitive helical coil, its supporting framework, and
connecting mechanism between it and the pointer.
Fig. 3. a side elevation of the parts shown in Fig. 2, and also of a portion of the
cutside case, the latter being shown in section.
Fig. 4 a transverse section on line X X Fig. 2.
ļ
Fig. 5 an end elevation showing the adjusting device, for the fixed end of the
sensitive helical coil.
Figs. 6 and 7 details of the rear portion of the enclosing case, and
Fig. 8 details of the arm for holding one end of the helical coil.
The temperature is indicated on a graduated dial a by means of a main pointer b
connected with an arbor c provided with a pinion d, see Fig. 4, meshing with a
toothed segment e having an arm e¹ connected with one end of the sensitive helical
coil f, the other end of which is made fast or held stationary by an attaching
device g, connected with an upright extended from a plate h, constituting the
frame-work for the sensitive helical coil and the connecting mechanisin between it
and the pointer, the said plate being attached to the dial plate a in any suitable
manner as by the screws h².
The axis or arbor c² of the toothed segment eis in line with the axis of the
sensitive helical coil f, which is at right angles to the axis c of the pointer, so that
the coil so formed l'es parallel with the dial plate thus economizing space and
making a more convenient instrument than those heretofore made in which the
axis of the sensitive coil is in line or parallel with that of the pointer so that
the said coil projects lengthwise from the dial plate.
The ends of the arbor e2 of the segment are pointed to form pivots and the steps
or bearings for said pivots are both adjustable in the direction of the axis of the
arbor, the said steps in this instance being made as screws e supported in pro-
jections i of a bridge connected with the plate ³, the said bridge also constituting
a bearing for one end of the arbor c.
By making the steps e³ adjustable as described, the toothed segment e may be
readily set to mesh properly with the pinion d, a matter which would otherwise
be difficult to accomplish.
The arm g for supporting the fixed or stationary end of the sensitive helical coil
is provided with a clamping device g¹, shown as a set screw for engaging one end
of the said coil, which may thus be made fast at any desired distance from its end
in order to vary the length of its effective portion between the said aring and the
point of attachment of the said coil to the toothed segment, thus the dials, pointers,
and connecting mechanism between the latter and the sensitive helical coil may all
be made uniform, so that if when assembled in the thermometer it should be found
by testing that the amount of movement is too great or too small for a given
change in temperature, the clamping device g¹ may be loosened and the sensitive
helical coil be taken up or let out, to shorten or lengthen as may be required the
portion between the points of attachment of the said coil, thus decreas ng or
increasing its effect on the pointer until the proper adjustment has been secured.

page_text: In order to set the pointer at the proper position on the dial after the adjustment
of the helical coil has been made, as just described, the aring is connected with a
shaft g2 turning in the upright hand provided with an arm g³ engaged by an
adjusting screw 9 to produce a minute or slow movement of said arm and
connected arm g, by which the entire helical coil is moved bodily without changing
the relative position of its attaching points, and thus through the gear and pinion
also moving the pointer b until it is in exactly the right position.
The shaft g may be turned independently of the arm g³ to bring the pointer
nearly into correct position, within the range of movement provided for by the
screw g, after which the arm g³ is made fast on the arbor g2 by a set screw g³.
The entire instrument is enclosed in a case composed of a ring A, see Fig. 1,
forming a frame over the dial, which is preferably covered with glass, and a back
plate B provided with an opening B' opposite the adjusting screw g, the said
opening having a removable cap B³ provided with projections B, see Fig. 7, which
pass through notches B5 in the plate, and by a partial turn engaging said plate,
fastening the cap or cover in position to close the opening B2, as shown in Fig. 6,
thus by removing the cap B² a screw driver may be inserted, and the screw
turned to adjust the position of the pointer after the instrument is put together
and enclosed in its case.
The pointer b which is moved by the sensitive helical coil to indicate changes in
temperature is provided with a pin or projection b¹ cooperating with secondary or
registering pointers p'p', pivoted on a stationary hub or center piece surrounding
the pointer arbor c the said registering pointers p p', remaining stationary until
moved by the projection 61 of the pointer b.
The pointer p is caused by the projection b¹ to accompany the pointer b in its
movement in one direction, and the pointer p¹ accompanies the pointer bin its
movement in the other direction, each pointer 2 p¹, being carried by pointer bas
far as the latter moves in one or the other direction, the secondary pointer remaining
stationary on the return movement of the main pointer b so that the pointers p pl
will remain as left by the pointer b, thus indicating the maximum movement of
the pointer b in either direction.
P
In order that the indications of the pointers p p¹ may not be confused with the
reading of the main pointer b, the said registering pointers pp' are made shorter
or smaller than the main pointer b, and cooperate with a secondary dial or series
of graduations a¹.
In order to relieve the sensitive helical coil composed of a bi-metallic strip from
lengthwise strain between its' points of attachment, the arm g is connected with
the arborg by a joint gs which permits said arm to rock slightly on the arbor g³
to accommodate any movement of the end of the coil connected with the said arm
in a direction parallel with the axis of the said coil, without however permitting
the said end of the coil engaged by the clamping device g' to have any movement
around its axis.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1. A thermometer comprising a graduated dial and pointer; a sensitive helical
coil consisting of a bi-metallic strip located at the rear of the dial and baving its
axis parallel thereto; and connecting mechanism between the said coil and pointer
by which the twisting movement of the coil about its axis produces rotary move-
ment of the pointer about an axis at right angles to that of the coil, substantially
as described.
2. The pointer and pinion, combined with a sensitive helical coil and toothed
segment connected with one end thereof and meshing with the said pinion, and the
adjustable steps or bearing pieces for the arbor of the said segment, substantially
as described..

page_text: 3. The pointer, and sensitive helical coil and connecting mechanism between the
said pointer and one end of the said coil, combined with a clamping device adapted
to hold the said coil at any desired point near its other end and means for adjusting
the position of the said clamping device about the axis of the coil, substantially
as described.
4. A thermometer comprising a pointer and sensitive helical coil, and connecting
mechanism between the said pointer and one end of the said coil, and a holding
and adjusting device for the other end of the said coil consisting of an arbor and
arm connected therewith and an adjusting screw cooperating with the said arm,
and a second arm connected with the said arbor and provided with a clamping
device to engage the sensitive helical coil at the proper point near its end, and au
enclosing case for said parts provided with a removable cap affording access to the
adjusting screw, substantially as described.
5. The combination of a main pointer with secondary pointers of different size
or length, actuated thereby, and independent series of graduations cooperating
with the said main and secondary pointers, substantially as.and for the purpose
described.
Dated this 19th day of November 1885.
WM BROOKES & SON,
55 & 56 Chancery Lane, London,
Agents for the said Alfred George Brookes.