IMPROVEMENTS IN THE METHOD OF AND IN APPARATUS FOR ASCERTAINING THE TEMPERATURE OF HOT BLAST OB OF HEATED GASES, PARTLY APPLICABLE TO PYROMETERS OTHERWISE USED.
Year: 1873

page_text: LETTERS PATENT to Henry Hobson, of Workington, in the County of
Cumberland, Manager, for the Invention of "IMPROVEMENTS IN THE
METHOD OF AND IN APPARATUS FOR ASCERTAINING THE TEMPERATURE OF HOT
BLAST OB OF HEATED GASES, PARTLY APPLICABLE TO PYROMETERS OTHERWISE
USED.
"
Sealed the 8th August 1878, and dated the 5th April 1873.
PROVISIONAL SPECIFICATION left by the said Henry Hobson at the
Office of the Commissioners of Patents, with his Petition, on the
5th April 1878.
I, HENRY HOBSON, of Workington, in the County of Cumberland,
Manager, do hereby declare the nature of my said Invention for "Im-
PROVEMENTS IN THE METHOD OF AND IN APPARATUS FOR ASCERTAINING THE
TEMPERATURE OF HOT BLAST OR OF HEATED GASES, PARTLY APPLICABLE TO PYRO-
METERS OTHERWISE USED," to be as follows:-
My Invention relates more particularly to the hot blast employed in

page_text: :
The pyrometers as ordinarily employed to ascertain the temperature
of a hot blast are exposed to high temperatures, which cause the instru-
ments to deteriorate and to give irregular or unreliable indications.
The object of my said Invention is to remedy this defect, and to this
end I dilute the hot air of a hot blast with cold air, that is to say, with
air which has not been artificially heated, and I ascertain the temperature
of the mixture by means of a thermometer or pyrometer, and if tho
proportions of hot and cold air thero or thereabouts be known the
temperature of the hot blast may be ascertained with sufficient accuracy
by means of a simple calculation, or the scale of the thermometer or
pyrometer may be graduated to indicate the calculated temperature of
the blast. I prefer to effect the reduction of the temperature of the hot
air by bringing together and causing to mingle two streams of air, one
from the hot blast and the other from a cold or unheated blast, the
mixture being afterwards brought into contact with the thermometer or
pyrometer, but if preferred or if it is not convenient to supply a cold
blast the cold air may be derived from the atmosphere surrounding the
apparatus by the inductive action of a jet of hot blast air.
Any suitable thermometer or pyrometer may be employed, but when
a pyrometer is used I prefer to employ a wire of platinum or other suit-
able metal, which in order to render the instrument more compact is
wound several times around a double set of pulleys in a manner similar
to the rope in a pair of blocks. One end of the said wire is attached to
a fixed point, the other end being attached to or connected with the
index or with a suitable self-registering apparatus. The said wire and
pulleys may be mounted within an earthenware tube, through which the
mixture of hot blast and cold air may be caused to flow when it is
desirable to ascertain the temperature of the hot blast, or the said pulleys
may be kept apart by any other suitable substance or material which
does not expand at the same rate under the influence of heat as the
metal wire.

page_text: I may employ multiplying drums or pulleys connected together by
means of chains, wires, or bands to increase the relative motion of the
index. This part of my Invention or modifications thereof may be
employed to ascertain the temperature of hot blast without an admixture
of cold air or to act as a pyrometer for other purposes.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
HOBSON, of Workington, in the County of Cumberland, Manager, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of April, in the year of our
Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Hobson, Her special license that I,
the said Henry Hobson, my executors, administrators, and assigns, or
such others as I, the said Henry Hobson, my executors, administrators,
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 "IMPROVEMENTS IN THE METHOD OF AND IN
APPARATUS FOR ASCERTAINING THE TEMPERATURE OF HOT BLAST OR OF HEATED
GASES," upon the condition (amongst others) that I, the said Henry
Hobson, by an instrument in writing under my hand and seal, 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 Henry Hobson, do hereby declare
1
1

page_text: performed, to be particularly described and ascertained in and by the
following statement and accompanying Drawings, that is to say :-
My Invention relates more particularly to the hot blast employed in
the smelting of iron, but may also be applicable in other cases wherein
it is desirable to ascertain the temperature of a hot blast or of heated
gases.
The pyrometers as ordinarily employed to ascertain the tempera-
ture of a hot blast are exposed to high temperatures, which cause the
instruments to deteriorate and to give irregular or unreliable indica-
tions.
The object of my said Invention is to remedy this defect, and to this
end I dilute the hot air of a hot blast with cold air, that is to say, with
air which has not been artificially heated, and I ascertain the temperature
of the mixture by means of a thermometer or pyrometer, and if the
proportions of hot and cold air there or thereabouts be known the
temperature of the hot blast may be ascertained with sufficient accuracy
by means of a simple calculation, or the scale of the thermometer or
pyrometer may be graduated to indicate the calculated temperature of the
blast. I prefer to effect the reduction of the temperature of the hot air
by bringing together and causing to mingle two streams of air, one from
the hot blast and the other from a cold or unheated blast, the mixture
being afterwards brought into contact with the thermometer or pyro-
meter, but if preferred or if it is not convenient to supply a cold blast
the cold air may be derived from the atmosphere surrounding the
apparatus by the inductive action of a jet of hot blast air.
Any suitable thermometer or pyrometer may be employed, but when
a pyrometer is used I prefer to employ a wire of platinum or other
suitable metal, which in order to render the instrument more compact is
wound several times around a double set of pulleys in a manner similar
to the rope in a pair of blocks. One end of the said wire is attached to
a fixed point, the other end being attached to or connected with the
index or with a suitable self-registering apparatus. The said wire and
pulleys may be mounted within an earthenware tube, through which
the mixture of hot blast and cold air may be caused to flow when it is
desirable to ascertain the temperature of the hot blast, or the said
pulleys may be kept apart by any other suitable substance or material

page_text: which does not expand at the same rate under the influence of heat as
the metal wire.
In some cases or if preferred separate lengths of wire may be con-
nected together by means of levers, which take the place of the said
pulleys. This part of my Invention or modifications thereof may be
employed to ascertain the temperature of hot blast without an ad-
mixture of cold air, or to act as a pyrometer for other purposes.
And in order that my said Invention may be fully understood I will
now refer to the accompanying Sheet of Drawings illustrative of the
manner in which my Invention may be carried into effect, the said
Drawings being marked with letters of reference, corresponding marks
indicating the same parts in the various Figures.
Fig. 1, partly in section and drawn about one-fourth of the full size,
represents a form of apparatus in which hot and cold blast are mingled,
a being the hot blast pipe and b a tube which communicates with the
pipe or main which contains the cold or unheated blast.
The apparatus is adapted to be permanently attached to the hot blast
pipe, so that the temperature of the blast may be ascertained at any
time by opening the taps c, d. When the said taps are opened the hot
and cold air flow into and through a tube or chamber e, and issue
through the tap c. The bulb of a mercurial or other thermometer fis
exposed to the mingled currents, and the scale of the said thermometer
indicates the temperature of the said mingled currents. In this example
each blast issues into the chamber e through an aperture formed in a
disc, which can be changed if desirable. The two apertures may be of
one size, or may differ in size, bearing known proportions one to the
other, or there may be more than one aperture for each blast or for one
blast, as for example the cold air may issue through two or more
apertures of a certain size, and the hot air through one aperture of the
same size.
It may be desirable to make the chamber e longer than is represented
in order to ensure the mingling of the blasts before they reach the bulb
of the thermometer.
Fig. 2 also partly in section illustrates a modification in the apparatus.
In this example the thermometer is detached from the apparatus, and is
only applied thereto when a reading of temperature is to be obtained.

page_text: A conical end is formed on the tap c, and a correspondingly coned orifice
is formed in the end of the chamber g, which contains the bulb of the
thermometer f. The chamber g is furnished with a handle h made of
wood or other slow conducting material in order that it may be carried
in the hand and be applied to the blast-mingling apparatus. When
applied on the conical end of the tape the two taps are opened and
the mingled blasts flow through the chamber 9 and issue through an
orifice i. In this arrangement one thermometer may be employed in
connection with several sets of blast-mingling apparatus. In this and
the preceeding examples the two blasts issue into the mixing chamber
in directions at right angles to each other, but this may be varied, as
for example the two blasts may issue and enter the said chamber in the
same direction or in opposite directions.
Figs. 3 and 4 represent forms of apparatus in which the cold blast is
dispensed with.
In Fig. 3 the hot blast issues through a nozzle k into a chamber 7,
which is formed with openings m, m, through which air is drawn by the
inductive action of the issuing blast, the hot blast mingling with the
inducted air. The mingled currents, after acting upon the bulb n of a
thermometer leave the apparatus through an orifice at o.
€
In Fig. 4 is represented a portable form of apparatus adapted to be
applied to a sight-hole" of a blast furnace. This apparatus is formed
with a cone p of a form to suit the sight-hole q, and in the said cone is
fixed a tube r, which extends into the mixing passage 8, which is formed
with an inlet orifice t for air, and with an outlet orifice u for the issue of $
the mingled currents. The bulb of a thermometer v is exposed to the
air flowing through the said passage.
The apparatus is provided with a wooden handle w by means of which
it may be transported and be applied to the sight hole.
The action of the apparatus will be understood from what is herein- a
before contained.
Figs. 5 and 6 represent a pyrometer constructed in manner according
with a part of my Invention. In this example seven wires x, are
connected together by means of levers y, y, which
frames z, z¹, which are fixed in the ends of a tube a¹.
the series is attached by one end to the frame z¹, the
are mounted in
The first wire in
last wire being

page_text: jointed by one end to the lever 6', the arrangement being such as that
any alteration in the length of any one of the wires causes a movement
to be imparted to the ends of the said lever about equal to the said
alteration in length, so that for example supposing each wire to expand
and that the tube a¹ does not expand, the end of the said lever will be
moved through a distance equal to the collective expansion of all the
wires or thereabouts. The lever 6' is fixed on a spindle, which imparts
motion to the index in the manner indicated by dotted lines in Fig. 5, or
in any other suitable manner, or by any suitable combination of multi-
plying drums, pulleys, levers, or gearing. In this example the pyrometer
is provided with two inlet passages c¹, c¹, the one for cold blast, and the
other for hot blast air, and the mingled blasts are allowed to flow through
the tube a and to act on the wires x, x.
It is advisable to make the parts within the tube a¹ wholly or partially
of a non-oxidisable metal, or to coat such parts therewith. This part of
the apparatus may however be varied as may be required, and also the
number of wires and levers may be varied. I may use drums or pulleys
and a continuous wire of a round, flat, or other suitable form, as herein-
before indicated, in place of levers and separate lengths of wire, but I
have chosen for illustration the arrangement which I consider to be most
suitable.
It may
be of advantage to connect the two frames z, 2¹, with an outer
tube or with rods or bars of wood or other material, situated without the
tube a¹, and therefore not so liable to be affected by the heat of the air or
gases flowing through the said tube.
Having now fully described and indicated the nature of my said
Invention I would in conclusion have it to be understood that I claim,―
First. The employment of apparatus in which currents of heated and
unheated blast are mingled, substantially as and for the purpose herein-
before set forth and indicated.
Secondly. The apparatus illustrated by Figs. 3 and 4 in the accom-
panying Drawings and modifications thereof, substantially as herein-
before set forth and indicated.
Thirdly. The employment in apparatus for indicating temperature of
wires connected by levers or wound on double sets of pulleys, substan-
tially as herein-before set forth and indicated.

page_text: And lastly. The apparatus substantially as and for the purpose herein
set forth with reference to the accompanying Drawings.
In witness whereof, I, the said Henry Hobson, have hereunto set
my hand and seal, this Third day of October, in the year of our
Lord One thousand eight hundred and seventy-three.
E
HENRY HOBSON. (L.§.)