CERTAIN IMPROVEMENTS WHICH PREVENT EITHER THE EXPLOSITION OR THE COLLAPSE OP STEAM AND OTHER BOILERS FROM AN EXCESS OF EXTERNAL OR INTERNAL PRESSURE
Year: 1833

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
COOPER DOUGLAS, of Great Ormond Street, in the County of Middlesex,
Esquire, send greeting.
WHEREAS His most Excellent Majesty William the Fourth, did, by His
Letters Patent under the Great Seal of that part of the United Kingdom
of Great Britain and Ireland called England, bearing date at Westminster,
the Nineteenth day of November, in the fourth year of His reign, give
and grant unto me, the said John Cooper Douglas, my executors, admi-
nistrators, and assigns, His especial license, full power, sole privilege and
authority, that I, the said John Cooper Douglas, my executors, administrators,
and assigns, during the term of years therein mentioned, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town of
Berwick upon Tweed, my Invention of "CERTAIN IMPROVEMENTS WHICH PREVENT
EITHER THE EXPLOSITION OR THE COLLAPSE OP STEAM AND OTHER BOILERS FROM
AN EXCESS OF EXTERNAL OR INTERNAL PRESSURE;" in which said Letters Patent
there is contained a proviso that I, the said John Cooper Douglas, shall cause
a particular description of the nature of my said Invention, and in what
manner the same is to be performed, by an instrument in writing under my
hand and seal, to be enrolled in His Majesty's High Court of Chancery
within six calendar months next immediately after the date of the said in part

page_text: recited Letters Patent, reference being thereunto had, may more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Cooper Douglas, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be known and performed, are
particularly described and ascertained in and by the following description 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 a piston moved by the elasticity of the steam, by
means of which the common arrangement of a safety valve may be rendered
more certain in its operation, and my Invention also consists of a pneumatic
or hydraulic apparatus, or both. On the Drawing hereunto annexed these
provisions for safety are exhibited. Figure 1 is the side elevation of a boiler,
wherewith it is intended to generate and employ low pressure steam, with my
improvements attached and adapted thereto; part of this boiler is represented
open or enclosed, in order that my said improvements may be more distinctly
exhibited by the Drawing. Figure 2 is the end of a boiler wherewith it is
intended to generate and employ steam of a high pressure, with part of my
improvements attached thereto. Figure 3 is also the end of a high pres-
sure steam boiler, with that part of my improvements shewn in Figure 2
attached to it; this last arrangement, Figure 3, being merely exhibited
here to shew how the situation of the bell B and valve C may be altered
for purposes of convenience. My improvements may be said to consist of
two distinct arrangements for insuring safety to boilers, generators, caldrons,
stills, or other vessels subject to changes of pressure, whether external or
internal, by increase or decrease of temperature, or otherwise. When I wish
to guard such vessels against too great an increase of internal pressure, I apply
my improvements, shewn at A (Figure 1), in such manner that they shall insure
the opening of a safety valve of the usual description, by acting upon the lever
or other part of the usual safety valve arrangement, shewn at B (Figure 1). I
construct a small cylender above the point A, or other convenient part of my
said vessel, and fit into the cylinder a piston. As the piston rod C (Figure 1)
rises or falls in the small cylinder, by the increase or decrease of pressure
within the vessel, it is made to operate upon the chains D, E, (Figure 1.)
Connected with the chain E will be seen a small steelyard, spring balance, or
other well-knowu indicator of pressure G, suspended from the fixed bracket F.
When the piston rod C ascends, this chain E is acted upon, and the index
hand of the spring balance G will (in this particular arrangement) be seen to
have moved downwards. When the piston rod C descends, the pull upon

page_text: the chain E is lessened, and the index hand of the spring balance G will (in
this particular arrangement) be moved upwards. I have said that the chain D
is operated upon by the rise and fall of the piston rod C. One end of the
chain D is passed through a hole in the end of the safety valve lever at T,
in such manner that it shall have a little play without disturbing the safety
valve by every fluctuation and variation of pressure, which may affect the
piston rod C, and the indicator G. But if the pressure should continue to
increase, and should the safety valve at B not blow itself open, the ascending
motion of the piston rod C will very soon cause the chain D to pull upon the
safety valve lever, and cause (or contribute to cause) the opening of the safety
valve. My improvements described above, or modifications of them, I
consider applicable as the means of greater safety where the causes of boilers
or other vessels bursting are such as are generally acknowledged. But as I
have, from long experience and observation, been led to believe that some
explosions are attributable to other causes, I have provided for such peculiar
cases by the apparatus shewn on Figure 1, H, I, K, L, M, N, and O, for low
pressure boilers or other vessels; and by the apparatus shewn on (Figure 2)
P, Q, or by the apparatus shewn on (Figure 3, R, S, for high pressure
boilers or other vessels. These latter cases of explosion I attribute to the
water or other liquid being raised up from the bottom of the boiler by the
rapid formation of elastic vapour, which cannot with sufficient rapidity pass up
through to the surface of the liquid; such an elastic vapour, being a bad con-
ductor of heat, becomes more highly charged with heat, and with the more
power repels and drives upwards the liquid, forcing the steam off by the valve,
and sometimes the water also. When in such cases the valve is shut, the
deflected forces cause a showering of the upper and cooler liquid amongst
the lower or hotter elastic yapour, by which this hotter elastic vapour is
condensed, or partially condensed, and the pressure is thus suddenly reduced
below the pressure of the atmosphere; I therefore provide the low pressure
boiler with a supply of water ready to rush in below when this reduction of
pressure takes place in the inside, as at (Figure 1), and I provide the high
pressure boiler with a supply of atmospheric air to rush in, as at Figures
2 and 3. In low pressure boilers I use the arrangement of cisterns
(Figure 1). When the internal pressure is too little, and a collapse likely
to happen, the hanging valve K will be pressed open by atmospheric
pressure, and water from the cistern No. 1 will flow into the boiler
along K, I, H. For keeping No. 1 well supplied with water, I use
the common float apparatus L, M, by which means water is permitted to
flow down N from No. 2, when required, in No. 1. In some situations, and

page_text: particularly in steam boats, a mere pipe and valve O from the bottom of the
boiler into the water will answer the same purpose for either high or low
pressure, and may then be better than the cisterns No. 1 and No. 2.
In high
pressure boilers I prefer using the arrangement of a pipe and valve with signal
bell, shewn in Figure 2), and air is pressed in through the valve Q, and through
the pipe P, when necessary, to prevent a collapse. The signal bell W is
intended to warn the engineer that such change has taken place. In some
situations 1 prefer the air pipe, valve, and bell to be arranged as on Figure 3),
at R, S, X.
I have now described my certain improvements which prevent either the
explosion or collapse of steam and other boilers from an excess of external or
internal pressure," with reference to the annexed Drawing, in such manner as
to enable persons conversant with works of a similar nature to practise the
Invention.
And I do hereby declare that I do not claim as my Invention the use of a
steelyard, spring balance, or other meter of pressure; but I claim as my In-
vention, that construction and arrangement of a piston and cylinder (more
particularly above described) whereby the increase or decrease of pressure
within a vessel may be availed of for moving any of the numerous forms of
safety valves in use.
I do not limit my claim to any arrangement of connecting chains, connecting
rods, or other connection or connections between the said piston and the said
safety valve or safety valves, and I do not limit my claim to any kind of boiler
or boilers.
Further, I do not claim as my Invention the use of valves opening inwards,
and which have been extensively introduced in this country for some years,
for greater security to boilers when they are cooling; my claim is for the
construction, application, and use of such valves and tubes opening inwards
at the bottom of boilers (whatever be the position of such apparatus and valves)
for the purpose of counteracting the effects of those particular changes (more
distinctly above described) which I have observed to go on more or less in all
boilers.
And I do not limit my claim to that form and construction of the apparatus
which I have thought it adviseable to describe above.
In witness whereof, I, the said John Cooper Douglas, have hereunto set
my hand and seal, this Seventeenth day of May, in the year of our
Lord One thousand eight hundred and thirty-four.
JOHN COOPER (L.S.) DOUGLAS,

page_text: AND BE IT REMEMBERED, that on the Seventeenth day of May, in the
fourth year of the reign of His Majesty King William the Fourth, the said
John Cooper Douglas came before our said Lord the King in His Chancery,
and acknowledged the instrument aforesaid, and all and everything therein
contained and specified, in form above written. And also the instrument afore-
said was stamped according to the tenor of the Statute made in the fifty-fifth
year of the reign of His late Majesty King George the Third.
Talled Ahe Ninataonth day of Mov One thousand eight hundred and