CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1822

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
STEPHENSON, of Killingworth, in the County of Northumberland, Engineer,
send greeting.
'
WHEREAS His Majesty King George the Fourth, by His. Letters Patent
under the Great Seal of Great Britain, bearing date at Westminster, the
Twenty-first day of March, in the third year of His reign, did give and
grant to me, the said George Stephenson, my exors, admors, and assigns, or
such others as 'I, the said George Stephenson, my exors, adñors, 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 "CERTAIN IMPROVEMENTS IN STEAM
ENGINES;" in which the said Letters Patent there is a proviso: obliging me, the
said 'George Stephenson, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same to. be
enrolled in His Majesty's High Court of Chancery within two calendar
months next and-immediately..after the date of the said. recited Letters
Patent, as in and by the same, reference being thereunto had, will
appear.
more fully
NOW KNOW YE, that in compliance with the, said proviso, I, the said
George Stephenson, do hereby declare that the nature of my said Invention

page_text: and the manner in which the same is to be carried into effect, are particularly
described and delineated in and by the Figures and Drawings in the margin of
these Presents, and by the following description thereof, that is to say,-
It may, perhaps, tend more clearly to illustrate my improvement to point
out the defects of the present mode, and to shew wherein they are obviated by
my Invention.
Now, my Invention consists of a method or methods of producing a more
perfect vacuum than has hitherto been done in the condenser, consequently in
the cylinder of a single or double powered Bolton and Watt's engine, or
other engine where a condenser is used, or where the condensation is per-
formed in a vessel separate from the cylinder; and I hereby declare that the
same may be carried into effect in the following manner, that is to say :-
Figure 1 represents a side view of a construction of my Invention.
A, A, A, A, shew the cold water cistern, within which is the condenser B,
wherein the steam is condensed by a jet of cold water thrown in by the pipe f.
C is the air pump worked by a solid plunger e attached to the cross bar or
beam of the engine by the rod G. a and b are two clacks or hanging valves
for opening and shutting off the communication between the air pump and
the condenser; i is a similar valve through which the water is discharged
from the under side of the plunger into the hot well F; and o is a loose wooden
cover on the top of the air pump for discharging the water and air from the
upper side of the plunger into the hot well E. The communication pipe D is
made to project a little into the condenser, so that a part of the condensing
water is made to flow upon the plunger in its descent, and which ought to be
sufficient to occupy the space between the wooden cover o and the plunger
when the latter is at the summit of its ascent, this space would otherwise
contain air, or vapour of the same density with the external atmosphere, and
which would materially injure the purity of the vacuum in the condenser.
9, 9, are inverted cones respectively fixed to the under side of the wooden
cover o and plunger e, which prevent the abrupt contact with the water in the
ascending and descending stroke of the piston or plunger. To obtain a perfect
vacuum in the condenser of a steam engine is a desideratum of great value,
as the want of it lessens the effect of the engine, whilst every little approxima-
tion towards it increases the effect without in the least adding to the cost or
expence of working the engine. The method of condensing the steam in a
vessel separate from the cylinder is generally considered an Invention of the
ingenious Mr. Watt, and has since his improvements undergone little or no
alteration. This method is effected by means of a vessel distinct from the
cylinder, and called the condenser, into which the steam is allowed to flow at

page_text: every half stroke of the double powered engine, and at every whole stroke
of a single powered "engine, and is condensed by a jet of cold water; which
water, together with the air that unavoidably penetrates the packing and
joints or is extricated from the water, is pumped out by means of an air pump.
The construction of the air pump and condenser on Bolton and Watt's
principle being so well known, it will be unnecessary to enter into a minute
description of them; only it may be necessary to state that the air pump and
condenser are supposed to stand near each other, with a communication
between them at the bottom, shut off occasionally by a hanging valve. I shall
proceed to consider the action of this apparatus immediately after the con-
densation is effected by the jet of cold water entering into the condenser; this
water will then fill the communication pipe and ascend to a certain height
within the condenser, above which the air and some steam remaining uncon-
densed will be resting. Suppose the air bucket begins to ascend, a vacuum will
be formed beneath it, and the water, pressed upon by the elasticity of the air
and vapour in the condenser, is impelled through the hanging valve to follow
the buckett in its ascent. Now, as the air from its inferior specific gravity
will not descend through the water, it is evident that the water must be forced
out of the condenser until the air obtains a passage along the roof of the
communication pipe until it comes perpendicularly beneath the column of
water in the air pump, where it will by its specific levity ascend through the
water and occupy a space immediately underneath the falls of the air buckett,
and will, when the buckett has gained its full ascent, be discharged in the
next stroke of the engine through the upper valve into the hot well. It
follows then that the air or other steam in the condenser will always be of
that elasticity which is required to support a column of water corresponding
with the size of the air pump and the quantity of injection water used; hence
the vacuum is always found to be far from perfect. But this is not the only
imperfection in this mode. In steam engines where the bucket moves with
great velocity, as in winding engines, the sudden impulse of the bucket upon
the water in descending soon destroys that accuracy and nicety requisite
in this part of the steam engine, and still further tends to render the vacuum
imperfect. I shall now explain the operation in my Invention. When the
condensation is effected, the water by its superior gravity will immediately
fall to the bottom of the condenser, the air and vapour resting upon the
upper part. Suppose in this situation the plunger to be at the bottom of the
pump and beginning to ascend, leaving a vacuum below it, the water in the
condenser will flow down and along the communication pipe, through the
valve a, and follow the plunger so far in its ascent until it (the water) finds

page_text: its equilibrium with that remaining in the condenser. On the return of the
plunger the valve a shuts and the valve i opens, and the water is forced into
the hot well F, and as the plunger descends a vacuum is made above it; the
valve 6 then opens and allows the air and elastic vapour to occupy the space
above the plunger, which in its 're-ascent shuts the valve b, and discharges
the whole through the loose cover o into the hot well E. Here then it will
be seen that the air or vapour having no obstruction in entering the vacuum
above the plunger, except what arises froni the resistance of the hanging
välve b, which is made to move very freely, the vacuum must be considerably
more perfect than the mode heretofore used, and will approximate very
'nearly to that of the barometer. Hence, then, my Invention consists of a
method of discharging the air and water from the condenser by the action of
a double pump, in such a manner that the air in its escape from the condenser
meets with scarcely any sensible obstruction from the condensing water,
the air and water being so distinctly separated that the discharge of the
'former is effected chiefly by the ascent, and the discharge of the latter by the
descent of the plunger. In the annexed Drawings, I have shewn my
apparatus with its application to a steam engine, where the air pump is made
to work the whole length of the stroke of the engine, which, together with
the action both in the ascent and descent, will proportionably reduce the size
of my air pump. It is well known the present apparatus cannot be applied
to work the whole length of the stroke of the engine without proportionably
decreasing the purity of the "vacuum; but in my Invention "the increased
length of stroke increases the purity of the vacuum," and further proves the
superiority of the present 'Invention. An engine on my plan 'may from its
simplicity of construction be removed and erected upon a smaller space, and
at considerably less expense, than has hitherto been done.
In witness whereof, I have hereunto set my hand and seal, the Eighteenth
day of May, in the year of our Lord One thousand eight hundred and
twenty-two
GEORGE STEPHENSON. (L.S.)
Signed, sealed, and delivered (being first
duly stamped) in the presence of
THOMAS CARR,

page_text: AND BE IT REMEMBERED, that on the Eighteenth day of May, in
the year of our Lord 1822, the aforesaid George Stephenson came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
5 above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Inrolled the Twenty-first day of May, in the year of our Lord One
thousand eight hundred and twenty-two.