A NEW OR IMPROVED THERMOMETER FOR MEASUREMENT OF HIGH TEMPERATURES."
Year: 1880

page_text: LETTERS PATENT to Edward Fisher Bamber, of Hammersmith, in the County
of Middlesex, Civil Engineer, for an Invention of "A NEW OR IMPROVED
THERMOMETER FOR MEASUREMENT OF HIGH TEMPERATURES."
PROVISIONAL SPECIFICATION left by the said Edward Fisher Bamber at
the Office of the Commissioners of Patents on the 5th August 1880.
EDWARD FISHER BAMBER, of Hammersmith, in the County of Middlesex, Civil
Engineer. "A NEW OR IMPROVED THERMOMETER FOR MEASUREMENT OF HIGH
TEMPERATURES.'
"
My Invention relates to the construction of thermometers for measurement of
high temperatures. For this purpose I employ fusible metals, alloys, or other
substances, which are solid at ordinary atmospheric temperatures, and which remain
in a state of fusion at the temperatures between which they are employed, by
whose expansion and contraction within a tube or other vessel while in a fused
condition the temperature is measured. The substances which I find may be
advantageously used are tin, lead, bismuth, and their alloys, sodium, aluminium,
copper, under the restrictions contained in the following paragraph :-
Substances which burn in the air will not be available at or above the
temperatures at which they respectively burn, unless they are protected from air;
nor will substances which volatilize be available, except at temperatures below
those at which they volatilize; nor will substances be available which burn or
volatilize at or near their temperature of fusion, such as manganese, antimony, etc.;
nor substances which decompose on fusion; nor substances which may be
considered as practically infusible for the purpose contemplated, such as cobalt,
nickel, chromium, and others; nor silver, which absorbs air in large volumes
near its melting point.
I fuse the substance to be applied to the purpose aforesaid in, or I transfer it in
a fused state into a graduated tube or other vessel (hereinafter called a tube), or in
or into a tube having a graduated scale in connection with it, by means of which
graduated tube or scale the temperature to be measured is ascertained, or in or into
a vessel of the character of a reservoir or bulb (hereinafter called a reservoir),
connected with such tube.

page_text: When the thermometer is intended for indicating temperatures below that at
which the material known as "combustion tube glass" begins to soften, such glass
or other heat resisting glass may be used for the tube, and also for the reservoir.
When the thermometer is intended for indicating temperatures at or above that
at which "combustion tube glass" begins to soften, the tube and reservoir should
be formed of plumbago or some other refractory material. In that case the tube
should be open at the top, and a float of some such refractory material is placed on
the surface of the fused substance within the tube, which float by means of a
graduated stem attached, or a stem attached moving before a graduated scale, will
by its rise and fall indicate the temperature; or the float and stem may be
connected with and operate upon a multiplying apparatus. In graduating the
instrument allowance will have to be made for the effect of variation of temperature
upon the several parts of the instrument.
The tube, especially if formed of plumbago or other refractory material, should be
calibrated, so as to ascertain accurately its internal capacity throughout, and to
graduate it, or the scale used in connection with it correctly, and allowance for
corrections ascertained to be required may be otherwise provided for.
It will generally be advantageous before use to place the thermometer in a pot or
vessel containing the same metal or other substance as that in the thermometer,
and gradually to heat and fuse the metal or other substance in such pot or vessel,
by which means the substance within the thermometer may be more gradually
heated and fused, and what may be called the zero point of each thermometer may
be more accurately ascertained.
To prevent oxidation of the fused metal in the pot or in the tube of the
thermometer when open at the top, a film of plumbago powder, charcoal, or other
material for excluding air may be placed on its surface.
After use it will be advantageous to lower the temperature of the fused substance
in the thermometer gradually, so that it may not in solidifying remain within the
tube, or crack the tube or reservoir. This may be effected by placing the
thermometer on its ceasing to be used in an asbestos jacket or other bad
conductor of heat.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edward Fisher Bamber in the Great Seal Patent Office on the
3rd February 1881.
EDWARD FISHER BAMBER, of Hammersmith, in the County of Middlesex, Civil
Engineer. "A NEW OR IMPROVED THERMOMETER FOR MEASUREMENT OF HIGH
TEMPERATURES."
My Invention relates to the construction of thermometers for measurement of
high temperatures. For this purpose I employ fusible metals, alloys, or other
substances which are solid at ordinary atmospheric temperatures, and which
remain in a state of fusion at the temperatures between which they are employed,
by whose expansion and contraction within a tube or other vessel while in a fused
condition the temperature is measured. The substances which I find may be
advantageously used are tin, lead, bismuth, and their alloys, alluminium, copper,
under the restrictions contained in the following paragraph:
=
Substances which burn in the air will not be available at or above the tempe-
ratures at which they respectively burn unless they are protected from air, nor will
substances which volatilize be available except at temperatures below those at
which they volatilize; nor will substances be available which burn or volatilize
at or near their temperature of fusion, such as manganese antimony etc.; nor will
substances which decompose on fusion, nor substances which may be considered as
practically infusible for the purpose contemplated, such as cobalt, nickel, chromium,
and others, nor silver, which absorbs air in large volumes near its melting point.
I fuse the substance to be applied to the purpose aforesaid in, or I transfer it in
a fused state into a graduated tube or other vessel (hereinafter called a tube) or in
or into a tube having a graduated scale in connection with it, by means of which
graduated tube or scale the temperature to be measured is ascertained, or in or into
a vessel of the character of a reservoir or bulb (hereinafter called a reservoir)
connected with such tube.
When the thermometer is intended for indicating temperatures below that at
which the material known as "combustion tube glass "begins to soften, such glass
or other heat resisting glass may be used for the tube and also for the reservoir.
There are various means of filling the reservoir. Either a bulb may be blown
on a piece of glass tubing, and a small aperture may be left in the bulb through
which the molten metal may be poured in, the hole being afterwards closed; or a
short piece of tubing of relatively large diameter with a bulb or reservoir at its
end may be employed, through which the fused metal may be poured in, and then
a piece of glass tubing of small bore may be fused into this; or the tube with bulb
blown on may be placed in a crucible containing sand, heated to a temperature
slightly above that of the fusing point of the metal to be employed, and small
pieces, or filings, or wire of the metal may be dropped down the tube to be fused in
the bulb or reservoir; or the reservoir may be formed of plumbago or other
refractory material, and a tube of glass may be fixed into the top by means of
steatite or other known means; or the bulb may be filled in the manner employed
with mercury thermometers, care being taken that the tube shall be kept at a
temperature above the fusing point of the metal to be used; this is best done by
keeping it within a closed heated chamber, having a working hole through which
a pair of clippers can be used, and one transparent side, made of mica, glass, or
other refractory transparent material, through which the operations can be
observed.
As a practical example I will assume tin to be metal employed. The reservoir
having been filled in any of the ways indicated above, and the tube having suitable

page_text: divisions marked upon it, I place within the heated chamber, which is at a tempe-
rature a little above that of melting tin, a crucible or other vessel containing fused
lead, and having heat applied to it sufficient to keep the lead in a fused state. I
place in the fused lead a mercury thermometer, which will indicate temperatures
between the melting points of tin and lead. When the mercury thermometer
indicates a temperature of 334° C. (the fusing point of lead) I note the division to
which the tin rises in the thermometer that is being constructed; this division will
represent 334° C., and the divisions between this and that corresponding to the
level of the tin when just fused will indicate temperatures between 237° C., the
fusing point of tin and 334° C. If the tube is uniform each division will represent
an equal fraction of this total difference of 97° C. The two points 237° and
334° C. having thus been settled, the thermometer containing the tin is placed in a
crucible or other vessel containing sand, or in a heated chamber at the temperature
of fused lead, and the temperature is carefully raised until just before the boiling
point of the tin is reached, whereupon the mouth of the tube is closed by the blow
pipe, or the vapour of the metal may be employed to drive out the air, and the
tube may then be closed. The tube above the point 334° C. can be graduated in
divisions corresponding with those below, the thermometer scale being thus com-
pleted. As a corrective check it is useful to compare the divisions with those of a
mercury thermometer as far as its range permits.
In using lead as the fused material within the thermometer, the tin thermometer
may be employed as a standard, as the mercury thermometer was employed as a
standard for the tin thermometer. And in like manner materials having different
degrees of fusibility may be employed for continuing the scale by the use of
successive standards, as above described in respect of mercury, tin, and lead.
At temperatures above that at which combustion tube glass, or the most
refractory glass made, melts, a plumbago or other refractory reservoir, and tubo
may be employed, and aluminum or other metal or alloy not readily oxidisable
may be introduced into the reservoir. Upon this is placed a float of asbestos or
other refractory material having a stem of steel, platinum, or other refractory
material, according to the temperature to be measured. By fixing within the tube
a scale stem of the same material as the float stem, and extending it to the required
height above the top of the tube, so that variations of temperature may influence
the expansion of both stems equally, the use of correction tables may be dispensed
with. The stem may work in front of a graduated scale, or it may be connected to
a multiplying apparatus; and to correct the effect of expansion resulting from
conduction through the stem, the multiplying apparatus may be mounted on
material of the same kind as the stem. Without the use of a float the tube may
have a strip of mica let into a slit along its side and graduated, so that the
temperature can be ascertained by inspection.
In employing the thermometer the temperature around the tube above the bulb
should be somewhat higher than the fusing point of the metal within the bulb.
This may be generally ensured by dipping the whole thermometer and stem into
the substance whose temperature is to be measured, or by passing the thermometer
through a hole into the furnace chamber whose temperature is to be ascertained.
In other cases the tube may be kept at the necessary temperature by ineans of a
lamp or burner having a funnel enclosing the thermometer. Or the thermometer
may have a tubular compartment containing metal the same as that in the
thermometer itself, and the metal in this compartment may be kept in a
fused condition, thereby maintaining sufficient heat to fuse the metal in the
thermometer. It is generally better to keep the thermometer always sufficiently
hot to retain its metal in fusion, but when it is temporarily used it should be
withdrawn slowly from the source of heat, so that the whole of the fused material
may run down from the tube, and the reservoir should be placed in a jacket of
asbestos or other bad conductor of heat.
It will be generally necessary "before use " to place the thermometer in a pot or
vessel containing the same metal or other substance as that in the thermometer,

page_text: and gradually to heat and fuse the metal or other substance in such pot or
vessel, by which means the substance within the thermometer may be more
gradually heated and fused, and what may be called the zero point of each
thermometer may be more accurately ascertained. The heat should be applied to
the substance within the pot or vessel, from above downwards, so that the upper
portion of the material in the thermometer may fuse before the lower portion, and
so yield to the expansion of the lower portion. This may be effected by baving a
double casing to the pot, the material being within the annular space, and applying
heat to the upper portion; or without the use of a pot or vessel by applying heat
at the place where the reservoir and tube join.
To prevent oxidation of the fused metal in the pot, or in the tube of the
thermoineter when open at the top, a film of plumbago powder, charcoal, or other
material for excluding air may be placed on its surface.
Having thus described the nature of my Invention and in what manner the
same is to be performed, I claim,-
-
The use of fusible metals, alloys, or other substances which are solid at ordinary
atmospheric temperatures, and which remain in a state of fusion at the temperatures
between which they are employed within a tube or other veasel while in a fused
condition for the measurement of temperature by their expansion and contraction
within such a tube or other vessel.
In witness whereof, I, the said Edward Fisher Bamber, have hereunto set my
hand and seal, this Second day of February, in the year of our Lord One
thousand eight hundred and eighty one.
E. F. BAMBER. (L.S.)