A NEW INSTRUMENT FOR INDICATING TEMPERATURES BETWEEN WIDE Limits
Year: 1871

page_text: LETTERS PATENT to Gustav Siemssen, of Stockholm, in the Kingdom
of Sweden, but at present of No. 11, Fenchurch Buildings, in the
City of London, for the Invention of "A NEW INSTRUMENT FOR
INDICATING TEMPERATURES BETWEEN WIDE Limits.”
INDICATING TEMPERATURES BETWEEN WIDE LIMITS.”
PROVISIONAL SPECIFICATION left by the said Gustav Siemssen at
the Office of the Commissioners of Patents, with his Petition, on
the 12th April 1871.
I, GUSTAV SIEMSSEN, of Stockholm, in the Kingdom of Sweden, but
at present of No. 11, Fenchurch Buildings, in the City of London, do
hereby declare the nature of the said Invention for "A NEW INSTRUMENT
FOR INDICATING TEMPERATURES BETWEEN WIDE LIMITS," to be as follows:-
My Invention has reference to a new instrument principally intended
for measuring accurately high temperatures such as cannot be indi-
cated by the ordinary mercury thermometer, and which I term " aero-
pyrometer."
.

page_text: The essential feature of my Invention consists in exposing atmospheric
air contained in an air chamber to the heat to be measured and in
causing such air when expanded by the heat to press upon a volume of
mercury or other suitable fluid (contained in a vessel communicating
with the air chamber) so as to force such mercury or other fluid up
through a closed graduated tube which serves to indicate the tem-
perature by the height at which the mercury stands relatively to the
graduated scale.
My Invention consists furthermore in certain appliances to be here-
after described, whereby the above mentioned main features of my
instrument are enabled always to operate with unvarying accuracy no
matter under what conditions the instrument is employed.
I construct a closed air chamber with a tube of small bore com-
municating therewith, both of which are formed of a suitable refractory
material, by preference platinum. The tube is fixed in an air-tight
manner to another tube forming an extension thereof constructed by
preference of glass (in which case it is best fixed to the platinum tube
by blowing), and communicating with the upper end of a second
chamber or vessel containing mercury. The platinum tube should be
long enough to prevent the glass from melting, and the mercury vessel
ought to be sufficiently removed from the air chamber to prevent the
heat from causing the mercury to boil. To the lower end of the mercury
chamber is fixed a glass barometer tube with a vacuum or at least air
tight, sealed at the upper end, and provided with a graduated scale, up
which tube the mercury is forced by the pressure due to the expansion of
the heated air passing from the heated air chamber up through the tube
thereof into the top of the mercury vessel. In close proximity to the
mercury vessel is by preference placed an ordinary high range thermo-
meter, the bulb of which, together with the mercury vessel, may
advantageously be wrapped round with silk or felt so that any alteration
of temperature which would interfere with the regular working of the
instrument may be watched. The air chamber and lower part of the
air tube (which are inserted into the furnace or other locality of which
the heat is to be measured) may be protected by a surrounding metal
pipe or casing of which the part surrounding the air tube is filled in
with sand, cement, or other refractory material, the air chamber itself
being however left quite free to come in immediate contact with the
heat. Should the air chamber and its tube be made of glass (in which

page_text: case the instrument only will do to measure a heat of about 800° Faht.)
they are by preference not introduced directly into the furnace or other
locality but into a metal pocket placed therein. In order to ensure
that all those parts of the instrument which are situated outside the
furnace or locality of which the heat is to be measured shall not be
affected by the temperature of the surrounding air, and shall be as much
as possible constant in their action, they are with the exception of the
graduated part of the barometer tube enclosed in a casing filled with
sand or other suitable bad conductor of heat and by preference provided
externally with a steam jacket into which steam is introduced through
a pipe from any steam generator conveniently at hand. A hermetically
closed aperture may be provided in the upper part of the mercury vessel
for regulating the quantity of mercury and for connecting it to an air
pump in order by exhaustion to regulate the density of the air to the
degree required for causing the mercury to stand lower than it would
do on account of the barometrical pressure of the atmosphere. Sufficient
air must be left in the instrument to enable it to act with such an
expansive force when heated as will afford a considerable range of scale
in the barometer tube. The graduations of the scale may be most
conveniently made when the apparatus is fixed at the locality where
the temperature is to be measured and the lower degrees may be marked
by comparison with the ordinary high range mercury thermometer.
The above described acro-pyrometer may, for the purpose of testing,
be first exposed to the heat of boiling water or any other comparatively
low known temperature, and then to a very great heat, after which it
should be again tried in boiling water when it will be found to indicate
correctly such temperature, thus proving the accurate working of the
instrumcnt.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Gustav Siemssen in the Great Seal Patent Office
on the 11th October 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GUSTAV
SIEMSSEN, of Stockholm, in the Kingdom of Sweden, but at present of
No. 11, Fenchurch Buildings, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of April, in the year of our

page_text: Lord One thousand eight hundred and seventy-one, in the thirty-fourth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Gustav Siemssen, Her special licence that I,
the said Gustav Siemissen, my executors, administrators, and assigns,
or such others as I, the said Gustav Siemssen, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "A NEW INSTRUMENT FOR
INDICATING TEMPERATURES BETWEEN WIDE LIMITS," upon the condition
(amongst others) that I, the said Gustav Siemssen, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said Gustav Siemssen, do hereby declare
the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and
by the following statement thereof, reference being had to the accom-
panying Sheet of Drawings and to the figures and letters marked thereon,
that is to say :-
My Invention has reference to a new instrument principally intended
for measuring accurately high temperatures such as cannot be indicated
by the ordinary mercury thermometer, and which I term acro-
pyrometer."
"
The essential feature of my Invention consists in exposing atmospheric
air or other suitable permanently clastic gas contained in an air chamber
to the heat to be measured, and in causing such air when expanded by
the heat to press upon a volume of mercury or other suitable fluid
(contained in a vessel communicating with the air chamber) so as to
force such mercury or other fluid up through a closed graduated tube
which serves to indicate the temperature by the height at which the
mercury stands relatively to the graduated scale.
My Invention consists furthermore, in certain appliances to be
hereafter described whereby the above mentioned main features of

page_text: my instrument are enabled always to operate with unvarying accuracy
no matter under what conditions the instrument is employed.
I construct a closed air chamber with a tube of small bore commu-
nicating therewith, both of which are formed of a suitable refractory
material, by preference platinum. The tube, which can be bent into
any convenient shape, is fixed in an air-tight manner to another tube
forming an extension thereof, constructed by preference of glass, and
communicating with the upper end of a second cylindrical formed
chamber or vessel containing mercury or a suitable fluid; the platinum
tube should be long enough to prevent the glass from melting and the
vessel for the mercury or the other fluid ought to be sufficiently
removed from the air chamber to prevent the heat from causing the
mercury or other fluid to boil. To the lower end of the mercury chamber
is fixed a glass barometer tube with a vacuum (or it may only be
air-tight sealed) at the upper end and provided with a graduated scale,
up which tube the mercury is forced by the pressure due to the
expansion of the heated air passing from the heated air chamber up
through the tube thereof into the top of the mercury vessel. In the
lower end of the barometer tube nearest the mercury chamber may be
provided an air-tight glass cock which when all the mercury has been
allowed to run into the upper end, leaving sufficient room for the
expansion of the mercury, can be shut, thus being of great advantage
for the safe transport of the instrument. In close proximity to
the mercury vessel is by preference placed an ordinary high range
thermometer, the bulb of which together with the mercury vessel
may advantageously be wrapped round with silk or felt, so that any
alteration of temperature which would interfere with the regular
working of the instrument may be watched. The air chamber and
lower part of the air tube (which are inserted into the furnace or other
locality of which the heat is to be measured) may be protected by
a surrounding metal pipe or casing of which the part surrounding
the air tube is filled in with sand, cement, or other refractory material,
the air chamber itself being however left free to come in intermediate
contact with the heat. Should the air chamber and its tube be made
of glass (in which case the instrument will only do to measure a heat
of about 800° Faht.) they are not introduced directly into the furnace
or other locality, but into a metal pocket placed therein. In case a
great heat requires to be measured the air chamber itself also
protected, for instance, by plumbago. In order to ensure
may
be
that all

page_text: those parts of the instrument which are situated outside the furnace
or locality of which the heat is to be measured shall not be affected by
the temperature of the surrounding air and shall be as much as
possible constant in their action, they are with the exception of the
graduated part of the barometer tube enclosed in a casing filled with
sand or other suitable bad conductor of heat, and by preference,
surrounded externally with boiling water or with a steam jacket into
which steam is introduced through a pipe from any steam generator
conveniently at hand. A hermetically closed aperture may be pro-
vided in the upper part of the mercury vessel for regulating the quantity
of mercury and for connecting it to an air pump in order by exhaustion
to regulate the density of the air to the degree required for causing
the mercury to stand lower than it would do on account of the
barometrical pressure of the atmosphere. Sufficient air must be left in
the instrument to enable it to act with such an expansive force when
heated as will afford a sufficient wide range of scale in the barometer
tube. The size of the bore of the latter also is of great influence in
this respect.
The lower graduations of the scale may be made by
comparison with the ordinary high range mercury thermometer, any
competent person will be able with their help and with due regard to
the cubical contents of the air chamber to make out the rest of the
scalc. The above described acro-pyrometer may for the purpose of
testing be first exposed to the heat of boiling water or any other
comparatively low known temperature, and then to a very great heat,
after which it should be again tried in boiling water, when it will be
found to indicate correctly such temperature, thus proving the accurate
working of the instrument.
On the accompanying Drawing is shown the construction of my
before described acro-pyrometer. Figure 1 shews the pyrometer
without a casing, and Figure 2 shows the same enclosed in a casing.
A is the vessel or chamber containing mercury or other suitable
fluid; B is the barometer tube hermetically closed at the upper end,
and communicating at the lower end with the bottom of the mercury
vessel A; B is the air-tight glass cock; C is the air chamber
communicating by means of the tube D, D', with the upper end of
the mercury vessel. The air chamber C and the lower part D of the
tube (which can be bent into any convenient shape) arc, by preference,
made of platinum or other suitable material that will withstand

page_text: considerable licat, while the other parts are made of glass, the tube D
being blown on to or otherwise secured to the tube D' in an air-tight
manner; D is a scaled branch opening through which the air contained
in the tube D, D', and air chamber C may in the first instance be partly
exhausted for the purpose before described; E is the scale graduated
as before described for indicating by the height of the column of
mercury in the barometer tube the temperature to which the air
chamber C is exposed. At Figure 2 the before described parts are
cnclosed in a metal casing F, F¹, F². The part F of this casing
enclosing the air vessel C and tube D, D¹, may be filled in with sand,
plumbago, or other refractory material, or only the tube may be
protected as described, and the air vessel be allowed to come into
immediate contact with the heat. In the furnace or other locality the
heat of which shall be measured a pocket may be arranged into which
is put part F of the instrument. Into the part F surrounding the
mercury chamber A (shewn in section) is introduced a high range
thermometer G, the bulb of which is placed in as close proximity as
convenient to the mercury vessel while the graduated tube thereof is
situated outside the casing as shewn. The mercury vessel and
thermometer bulb are wrapped round with silk, felt, or cotton wool,
and the casing F may be provided with a steam or hot water jacket
as before described. The part F of the casing surrounding the
barometer tube B has a longitudinal slot or opening f, through which
the height of the mercury in the tube may be observed, and by which
the tube is in free contact with the external atmosphere. Upon the
edge of the opening is marked the scale E from which the height of
the mercury is read off.
.
If desired for convenience of transport the instrument may be
constructed of two separate parts capable of being fitted together in an
air-tight manner, as at X, Figure 3.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I wish it to be understood that
what I claim is,―
First. The construction and use of an instrument for measuring tem-
peratures between wide limits, wherein the pressure obtained by the
expansive action of the heated air or other suitable permanently elastic
gas in a closed vessel or chamber is caused to force a column of mercury
or other fluid from a second vessel or chamber up a graduated tube

page_text: closed at the upper end, in order to indicate the degree of heat to which
the air chamber is exposed by the height of the mercury column in the
tube, substantially as herein-before described..
Second. I claim the combination of parts arranged and operating as
herein before described and shewn on the accompanying Drawings, con-
stituting a new instrument for indicating temperatures between wide
limits.
In witness whereof, 1, the said Gustav Siemssen, have hereunto
set my hand and scal, this Eleventh day of September, in the
year of our Lord One thousand eight hundred and seventy-one.