An Improved Construction of Pyrometer.
Year: 1892

page_text: Date of Application, 29th Aug., 1892
Complete Specification Left, 29th May, 1893-Accepted, 8th July, 1893
PROVISIONAL SPECIFICATION.
An Improved Construction of Pyrometer.
We HENRY PAUL JOSEPH NEGRETTI and MARCUS WARREN ZAMBRA both
of Holborn Viaduct in the City of London Scientific Instrument Makers do hereby
declare the nature of this invention to be as follows: :-
The object of this invention is to produce a simple and effective pyrometer at a
comparatively low cost, by which very high temperatures may be indicated.
In carrying out our invention, we take a thermometer, the tube of which may be
of suitable length and bore, with a suitable elongated bulb.
This tube we place in a metal case, which is inserted in the wall of the furnace
in the usual way, the bulb extending beyond the case. The other end of this tube
we may turn up at any convenient angle, and we provide it with a scale.
For safety, we enclose this scale in a suitable case, so formed, preferably, as to
permit of its being opened for inspection and closed again.
The bulb we enclose in a case of fire clay, carbon, platinum, or other substance
which will stand an intense heat without being readily fused, which case is secured
to the metal case in the wall in any convenient manner.
The effect to be produced will depend upon the conductivity of the material used
for the bulb case, which should be at least half as long again as the bulb, and
extend that much beyond it, so that the bulb may not come actually into contact
with the red hot portion.
Pyrometers constructed in this manner will not become practically destroyed
after a slight amount of use, as the bulb case may be renewed from time to time
with facility.
Dated this 29th day of August 1892.
NEWTON & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
An Improved Construction of Pyrometer.
We HENRY PAUL JOSEPH NEGRETTI and MARCUS WARREN ZAMBRA both
of Holborn Viaduct in the City of London, Scientific Instrument Makers, 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:-
The object of this invention is to produce a simple and effective pyrometer, at
comparatively low cost, for registering higher temperatures than can be indicated
with an ordinary thermometer.
The principle of the improved pyrometer is founded on the fact that heat
decreases in a geometrical ratio as it passes farther away from its principal
Bource.
In carrying out our invention, we employ a thermometer which we place in a
tube of some material which is more or less a conductor of heat to be inserted in
the fire or hot chamber, the temperature being indicated on a scale suitably placed
for the purpose.
And in order that our invention may be clearly understood, we will proceed to
fully describe it, reference being had to the accompanying drawing, in which
Fig. 1 is a side elevation, partly in section, of our improved pyrometer.
Fig. 2 is a front view, and
Fig. 3 a section on the line x, y, Fig. 1,-drawn to an enlarged scale.

page_text: A is the wall of the furnace, oven, or other hot chamber, and B is a socket which
is secured in the wall. C is a tube of iron, platinum, plumbago, or other suitable
material, which is conveniently secured, inside the hot chamber, to the socket B, so
that it may be readily replaced when burnt away.
D is a tubular case which is secured, outside the wall, to the socket B, and is
provided with a sliding or other door. Inside this case is arranged a scale in such
a manner that it may be readily seen when the door is open.
Inside the casing thus formed, we place a thermometer, the bulb. projecting into
the tube a greater or less extent, according to requirements, that is to say, the
lower the temperature to be indicated, the nearer the bulb will be placed to the
source of heat, and the higher the temperature, the further away from the source
of the heat.
The scale will be marked off in accordance with the position of the bulb in the
heat-conducting tube.
The heat will be conveyed to the bulb by the air, which, entering the scale case,
comes in contact with the heated portion of the conducting tube, becomes heated,
and then imparts its heat to the bulb in a geometrical ratio, as before stated, to the
distance the bulb is from the source of heat.
The material employed for the bulb case will depend upon the use to which the
apparatus is applied, that is to say, if the apparatus is to indicate very high
temperatures, plumbago or other comparatively bad conductor of heat will be
employed, whereas, for comparatively low temperatures, metals having a greater or
less degree of conductivity may be employed.
In some cases we may use an iron case surrounded by plumbago, as indicated by
dotted lines in Fig. 1.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
The improved construction of pyrometer substantially as herein shown and
described, in which the temperature is indicated by placing the bulb of a ther-
mometer at a greater or less distance from the source of heat, in a suitable
conducting medium, as set forth.
Dated this 29th day of May 1893.