CERTAIN IMPROVEMENTS IN THE CON- STRUCTION OF THE BOILERS AND FUNNELS OF STEAM ENGINES
Year: 1850

page_text: PIM'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WAKEFIELD
PIM, of the Town or Borough of Kingston upon Hull, in the County of the
same Town or Borough, Engine and Boiler Maker, and Builder of Iron Steam
Ships, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, under the Great Seal of the United Kingdom of Great Britain and
Ireland, bearing date at Westminster, the Third day of July, in the four-
teenth year of Her reign, did give and grant unto me, the said Wakefield Pim,
my exors, adñiors, and assigns, Her especial license, full power, sole privilege
and authority, that I, the said Wakefield Pim, my exors, adñiors, and assigns,
and every of them, by myself and themselves, or by my or their deputy or
deputies, servants, or agents, or such others as I, the said Wakefield Pim,
my exors, admors, or assigns, should at any time agree with, and no others,
from time to time, and at all times thereafter, during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend within that
part of the United Kingdom of Great Britain and Ireland called England,
the Dominion of Wales, and the Town of Berwick upon Tweed, and in the
Islands of Jersey, Guernsey, Alderney, Sark, and Man, and also in all Her
Colonies and Plantations abroad, in such manner as to me, the said Wakefield
Pim, my exors, admors, and assigns, or any of them, should, in my or their
discretion, seem meet, my Invention of "CERTAIN IMPROVEMENTS IN THE CON-
STRUCTION OF THE BOILERS AND FUNNELS OF STEAM ENGINES," and that I, the said
Wakefield Pim, my exors, adñors, and assigns, should have and enjoy the
whole profit, benefit, commodity, and advantage from time to time coming,
growing, accruing, and arising by reason of the said Invention, in which said

page_text: Letters Patent there is, amongst others, contained a proviso, that if 1, the
said Wakefield Pim, shall not particularly describe and ascertain the nature of
the said Invention, and in what manner the same is to be performed, by an
instrument in writing under my hand and seal, and cause the same to be
enrolled in Her said Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said recited Letters Patent,
that then the said Letters Patent, and all liberties and advantages whatsoever
thereby granted, should utterly cease, determine, and become void, any thing
therein-before contained to the contrary notwithstanding, as by the said Letters
Patent, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said recited proviso, I, the
'said Wakefield Pim, do hereby declare the nature of my said Invention,
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being had to
the Drawing therein referred to.
Tubular boilers as ordinarily constructed for marine steam engines are
greatly superior to those made with flues, as by their compact form the space
necessary in the vessel is much reduced, and by their comparative lightness the
draught of water is diminished, thereby rendering a greater proportion of the
tonnage of the vessel available for commercial purposes, and affording increased
-speed with the same propelling power. These advantages, although unquestion-
ably great, are much diminished by the rapid manner the flame and heated
gases pass immediately through the tubes, without duc circulation, into the
chimney; much of that heat which ought to be absorbed by the water in the
boiler being thus lost, and the destruction of the boiler and chimney, as also
the consumption of fuel, being increased in a corresponding degree. To remedy
.these serious defects is the object of my Invention, and the mode of effecting
this consists in giving a double circulation to the flame and heated gases
generated in the furnaces through the tubes, thus keeping their heating influ-
ence longer in contact with the water in the boiler, by which means a large
portion of that heat which usually and uselessly escapes up the chimney in
boilers as generally constructed, and occasions the rapid destruction of the
"chimney, and an extravagant consumption of fuel, is absorbed and beneficially
employed. For the purpose of shewing more distinctly how this object is
-accomplished, and the nature of my said Invention, a Drawing of my improved
tubular boiler is hereto annexed, in which Figure 1 shews a longitudinal section,
and 2 a transverse section. A. The furnace. B, B. Water spaces, which divide
the tubes into two distinct tiers. D. Chimney. The arrows shew the circulation
of the plane through the lower and upper tiers of the tubes into the chimney.

page_text: Figure 3 is a longitudinal section of a tubular boiler as usually constructed.
The flame, instead of passing at once through the flues into the chimney, as is
the case in a boiler constructed as in Figure 3, passes, as will be seen by the
Drawing, Figure 2, through the lower tier of tubes, and thence through the
upper tier into the chimney. The situation and construction of the funnel is
altered, as shewn in the Drawing, so as to admit of the circulation of the
flame, according to my Invention.
From the aforegoing statement and annexed Drawing it will be seen
that the double circulation herein-before mentioned is secured by the water
spaces, which it will be seen by the Drawing divide the tubes into two
tiers, and occasion the flame, &c. to pass through the bottom tier, pre-
viously to its entrance into the chimney through the top tier, thus doubling
the length of the circuit traversed by the flame, and affording sufficient time
for the water in the boiler to absorb all the heat which is not required to
produce the necessary draught in the chimney.
Having now described the nature of my Invention, and in what manner the
same is to be performed, I hereby declare the Invention whereof the exclusive
use is claimed by the said in part recited Letters Patent to consist, in con-
structing the boilers and funnels of steam engines so as to give a double
circulation to the flame and heated gases generated in furnaces of marine
steam engines, through the tubes as above described.
In witness whereof, I, the said Wakefield Pim, have hereunto set my
hand and seal, this Eighteenth day of December, in the year of our