IMPROVEMENTS IN ASCERTAINING AND INDICATING THE TEMPERATURE AND PRESSURE OF FLUIDS
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
DUNN, of Dalston, in the County of Middlesex, Chemist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twelfth day of October,
One thousand eight hundred and forty-eight, in the twelfth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Arthur Dunn, my exors, admors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Arthur
Dunn, my exors, adññors, and assigns, and such others as I, the said Arthur
Dunn, my exors, adiñors, or assigns, should at any time agree. with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "IMPROVEMENTS IN ASCERTAINING AND INDICATING THE TEMPERATURE AND
PRESSURE OF FLUIDS;" in which said Letters Patent is contained a proviso, that
I, the said Arthur Dunn, should cause a particular description of the nature of
my said Invention, and the manner in which the same is to be performed, by
an instrument in writing under my hand and seal, to be inrolled in Her

page_text: said Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Arthur Dunn, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, are fully described and ascer-
tained in and by the following statement thereof, reference being had to the
Drawing hereunto annexed, and to the figures and letters marked thereon
(that is to say)-
My Invention consists of so combining and applying thermometric appa-
ratus and electric currents as to ascertain the temperature and pressure of
fluids in vessels principally applicable to steam and other close boilers. My
Invention also consists of combining electric apparatus with pressure guages
in such manner as to ascertain and indicate when the pressure of a fluid
arrives at a determined point. And in order that my Invention may be most
fully and readily understood, I will proceed to describe the means pursued
having apparatus applied thereto according to my Invention, as will enable me
to describe my improvements. a is a tube descending into the boiler so as
to come just below the water line, and it is bent in such manner as to come in
contact with the side of the boiler. The tube a is securely fixed to the boiler,
as shewn, and it has the branch b fixed at its upper end, into which two tubes
c, d (which I prefer to be of glass), are fixed. The tubes a, c, d, and the
branch 6, are filled with mercury, as is indicated by the pink color, and there
is an iron float e in the tube c, with a piece of platina at its upper end. f is.
a standard fixed to the upper part of the boiler, but insulated therefrom by the
glass at g. At the upper part of the standard is the sliding piece h, which
may be slided up or down and fixed by a screw i. To the sliding piece h
is affixed the branch j, the stem of which being partly of glass, the plate
will be insulated. k is a lever which at one end is attached to the wire l,
which descends through a guide hole in the cup into the tube c, there being at
the lower end of such wire a point of platina, so that when the float rises there
will be an electric circuit formed, as hereafter explained. At the other end of
the lever is fixed a piece of platina, and there is also a piece of platina on
the under surface of the plate, so that when that end of the lever rests under

page_text: the plate j' there will be a continued line of metal contact between these parts;
'but a complete electric circuit will not be produced till the float in the tube c
rises and comes in contact with the wire therein. It should be understood
that the weight of the end of the lever connected to the wire is to be such as
to raise the other end of the lever, so that it may rest under the plate j', as
shewn. m is a wire fixed by a screw n to the plate "; this wire leads to a
bell apparatus at o, such as is used in electric telegraphs, and are well under-
stood, the object being to give notice of the rising of the steam after it has
been down; and in order to complete the circuit the wire passes from the bell
apparatus to a battery at p, there being a wire q from the other pole of the
battery to the branch b. By this arrangement so soon as the float rises in
contact with the wire, a circuit will be completed and the bell at o will ring;
but the continued rising of the float will raise the lever at one end and depress
it at the other, so as to put it out of contact with the plate j', and then so
long as the steam continues to be at the working pressure, the bell at o will
not again be called into action, the use of the bell at o being intended only to
indicate that the apparatus is in working order at the time of raising the
steam. In adjusting the position in the tube c, it is to be so placed as to be
acted on and raised so as to break the circuit before the working pressure of
the steam has been attained. This part of the apparatus is not essential, but
I prefer to employ the same in addition to what I will now proceed to explain.
In the tube d is a wire which is to set in such manner that its lower end,
which should be of platina, will come just above the quicksilver in the tube
when it stands thereon at the height which will be caused by the heat which
should produce the pressure of steam desired in the boiler, and therefore at
starting the apparatus is to be adjusted when the steam is at its working
pressure in the boiler, and when the wire in tube d has been adjusted it is to
be fixed by the set screw o* as shown. From the upper end of the wire in the.
tube d proceeds the wire r to the bell apparatus at s, and thence to the battery..
By this arrangement, when heat in the boiler rises above that which is
proper
for producing the desired pressure of steam in the boiler, an electric circuit will.
be completed, and the bell at s will continue to ring, and thus persons near or
at a distance will be informed that the temperature or pressure in the boiler is
greater than that which has been determined shall be the temperature or
working pressure in the particular boiler, the thermometric apparatus ascertain-
ing the temperature, and the electric apparatus indicating, either near or at a
distance, when the temperature and pressure rise too high. I have spoken of
a bell apparatus being used at only one place for each part of the apparatus,
but it will be evident that bells or other indicating apparatus may be used at

page_text: several places, and be simultaneously acted on by an clectric current, the
battery and connecting wires being suitably arranged accordingly. The
description of battery I have used is that known as Smee's, but this may be
varied, and the nature of the battery will, as is well understood, depend on the
extent of circuit and bell apparatus used. If desired the tube d may have a
graduated scale applied to indicate the temperature to the sight, so that the
same may be ascertained at any time.
I would remark that although this apparatus is chiefly intended for steam
and other boilers where fluids are being heated under pressure, and liable
to produce injurious effects if neglected after the heat and pressure have
risen beyond a certain extent, yet such apparatus may be applied to
ascertain and indicate, both near and at a distance, when the temperature of. a
fluid in a vessel has been raised to a determined degree of heat. When
carrying out my Invention by using a steam or pressure guage in place of
thermometric apparatus, I prefer for this purpose to use the ordinary glass
steam guage, and I introduce a platina wire at that height in the guage
which would come just above the working pressure, so that when the
pressure of the steam rises above the desired working pressure, the quick-
silver will be raised and it will come in contact with the platina wire,
which, being made part of an electric circuit, will act on a bell or other
indicating apparatus either near or at a distance. If desired several pla-
tina wires insulated from each other may be introduced at different heights
in the steam guage, and the circuit wire attached to that one which for
the time being comes just above the desired working pressure.
or wires are to be introduced in an air and steam-tight manner.
The wire
Having thus described the nature of my Invention, and the manner in
which the same is to be performed, I would remark that I make no claim
to any of the parts separately, nor do I confine myself to the details as
Inven-
herein shown and described, so long as the peculiar character of
tion be retained, But what I claim is the so combining and applying
thermometric and electric apparatus as to ascertain and indicate the tempe-
rature and pressure of fluids.
my
And I also claim the combining electric currents with steam or pressure
guages, so as to ascertain and indicate the pressure of fluids.
In witness whereof, I, the said Arthur Dunn, have hereunto set my hand
and seal, this Twelfth day of April, in the year of our Lord One
thousand eight hundred and forty-nine.
ARTHUR (L.S.) DUNN.

page_text: AND BE IT REMEMBERED, that on the Twelfth day of April, in
the year of our Lord 1849, the aforesaid Arthur Dunn came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Enrolled the Twelfth day of April, in the year of our Lord One thousand
eight hundred and forty-nine.