CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1805

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
WOOLF, of Wood Street, Spa Fields, in the County of Middlesex, Engineer,
send greeting.
WHEREAS is present most Excellent Majesty King George the Third,
in and by His Royal Letters Patent under the Great Seal of the United
Kingdom of Great Britain and Ireland, beaning date at Westminster, the
Second day of July, in the forty-fifth year of Ilis reign, for Himself, His
heirs and successors, did give and grant unto me, the said Arthur Woolf,
my executors, adınınistrators, and assigns, Ilis especial licence, full power,
sole privilege and authonty, that I, the said Arthur Woolf, my executors,
administrators, and assigns, and every of them, by myself and themselves, or
by my or the deputy or deputies, servants or agents. or such others as 1,
the said Arthur Woolf, my executors, administrators, or assigns. should at
any time agree with, and no others, fiom time to time and at all times there-
after 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 said Letters Patent there is contained a proviso obliging
me, the said Arthur Woolf, by an instrument in writing under my hand and
seal, particularly to describe and ascertam the nature of my sand Invention,
and in what manner the same is to be performed and to cause the same
to be inrolled in His said Majesty's High Court of Chancery within four
calendar months next and immediately after the date of the said recited

page_text: Letters Patent, as in and by the same Letters Patent, 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 Woolt, do hereby describe and ascertain the nature of my said Inven-
tion, and the manner in which the same is to be performed, as follows, that
is to say-
I have found out and invented a contrivance by which the temperature of
the steam vessel or working cylinder of a steam engine, or of the steam vessels
or cylinders where more than one aic used, may be raised to any required
temperature without admitting steam fiom the boiler into any surrounding
receptacle, whether known by the name of a steam case or by any other
denomination; that is to say, instead of admitting steam of an high tem-
perature into such receptacle or steam case, which is always attended with a
risque of explosion proportioned to the elasticity of the steam employed, I put
into the said surrounding receptacle or case oil or the fat of animals, or wax, or
other substances capable of being melted by a lower temperature than the heat
intended to be employed, and of bearing that heat without being converted
into vapour, or I put into the said case or cases mercury or mixtures of
metals, as of tin, bismuth, and lead, capable of being kept in a state of fusion
in a lower temperature than that intended to be employed in working the
steam engine, and I so form the surrounding case or cases as to make it or
them admit the aforesaid oil or other substance employed to come into contact,
not only with the sides of the steam vessel or vessels or working cylinder or
cylinders, but also with the bottom and top of the same, so that the whole
may be as much as possible maintained at one uniform temperature, and this
temperature I keep up by a fire immediately under o 1ound the case or cases
that contains the aforesaid oil or other substance or by connecting the said
case or cases with a separate vessel or vessels kept a proper temperature filled
with the oil or other substance made use of as aforesaid In some circum-
stances, or whenever the same may be made convenient or desirable, I employ
the fluid metals or mixtures of inetals. and oil or other of the substances
before enumerated, at one and the same time in the same engine, that is to
say, in the part of the case or vessel exposed to the greatest action of the fire
I sometimes have the atoresaid metals or mixtures of metals, and in the parts
less exposed to the action of the fire I put oil or other substances capable of
beanng the requisite heat without being converted into vapour By this
arrangement and method of applying the surrounding heat I not only obviate
the necessity of employing steam of a great expansive force 1ound the steam
vessel or vessels or the working cylinder or cylinders, as already mentioned,

page_text: to maintain them at the temperature required, but I am enabled to obtain
from steam of a comparatively low temperature, or even from water itself
admitted into the steam vessel or vessels, all the effects that can be obtained
from steam of an high temperature, without any of the sque with which the
production of the latter is accompanied not only to the boiler and other parts
of the machinery, but even to the lives of the workmen, for such low steam or
even water (but in every case steam is preferable) being admitted into a
steam vessel or vessels or working (linder or cylinders kept at the requisite
higher temperature by the afore-mentioned means, will there be expanded in
any ratio required, and produce an effect in the working of the engine which
cannot otherwise be obtained but at a greater expence of fuel, or with the
risque of an explosion By this means I can make use of steam expanded in
any requned ratio, or of any given temperature, without the necessity of
ever having the steam of any greater elasticity than equal to the pressure of
the comnion atmosphere
Another improvement which I make use of in steam engines consists in a
method of preventing, as much as possible, the passage of any of the steam
from that side of the piston which is acted upon by the said steam to the
other side which is open to the condensoi, and this I effect in those steam
engines known by the name of double engines, by employing upon or about
the piston mercury or fluid metal or metals in an altitude equal to the pics-
sure of the steam The efficacy of this arrangement will appear obvious fiom
attending to what must take place in working such a piston When the
piston is ascending, that is, when the steam is admitted below the piston.
the space on its other side being open to the condenser, the steam endeavour-
ing to pass up by the side of the piston is met and effectually prevented by
the column of metal equal or superior to it in pressure, and during the down
stroke no steam can possibly pass without first forcing all the metal through.
In working what is called a single engine a less considerable altitude of metal
is required, because the steam always acts on the upper side of the piston
For single engines oil or wax or fat of ammals or similar substances in suffi-
cient quantity will answer the purpose If another improvement, which con-
stitutes part of my said Invention, be applied to the engine, namely, to take care
that in either the double or single engine so to be worked the outlet that conveys
the steam to the condenser shall be so posited and of such a size, that the steam
may pass without forcing before it or carrying with it any of the metal or
other substance employed that may have passed by the piston, taking care at
the same time to provide another exit for the metal or other substance
collected at the bottom of the steam vessel or working cylinder to convey the

page_text: same into a reservoir kept at a proper heat, whence it is to be conveyed to
the upper side of the piston by a small pump worked by the engine or by any
other contrivance In order that the fluid metal or metals used with the
piston may not be oxidated, I always keep some oil or other proper fluid
substance on its surface to prevent its coming in contact with the atmosphere,
and to prevent the necessity of employing a large quantity of fluid metal, I
generally make my piston of the depth of the column required, but
of a diameter a little less than the steam vessel or working cylinder,
excepting where the packing or other fitting is necessary to be applied, so
that in fact the column of fluid metal forms only a thin body round the
piston. In some cases I make a hollow metallic piston, and apply an altitude
of fluid metal on the inside of the same to press its outside into contact with
the steam vessel or working cylinder. It may be necessary, however, to state
that in applying my improved method of keeping the steam vessels of steam
engines at any required temperature to the engine known by the name of
Savary's, in any of its improved forms in which a separate condenser has been
introduced, I sometimes employ oil (or any other substance lighter than
water, and capable of being kept fluid in the temperature employed without
being converted into vapour) in the upper part of the tube or pipe attached
to the steam vessel, by which means steam of any temperature may be used
without being exposed to the iisque of partial condensation by the admission
of any colder body into the steam vessel, for the oil or other substance
employed for this purpose soon acquires the requisite temperature And to
prevent unnecessary escape of heat 1 construct of or line with an imperfect
conductor of heat that part of the tube or pipe attached to the steam vessel
which may may not be heated exteriorly, and further (as is already the prac-
tice in some engines, and therefore not exclusively claimed by me,) cause the
water raised by the engine to pass off though another ascending tube than
the one attached to the steam vessel, but connected with it at some part lower
than the oil or other substance employed in it is ever suffered to descend to
in the working of the engine The improvement which I have just men-
tioned of introducing oil into the pipe attached to the steam vessel of such
engines may also be introduced without applying heat externally to the steam
vessel, but in this case part of the effect, which would otherwise be gained,
Is lost.
In witness whereof, I, the said Arthur Woolf, have hereunto set my
hand and seal, the First day of November, in the year of our Lord
One thousand eight hundred and five.
ARTE (L.S.) WOOLF.

page_text: AND BE IT REMEMBERED, that on the same First day of November,
in the year above mentioned, the aforesaid Arthur Woolf came before our
Lord the King in His Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained, in form above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute in that case made and provided.
Inrolled the Second day of November, in the year above written.