IMPROVEMENTS IN GENERATING STEAM FOR CONDENSING ENGINES."
Year: 1859

page_text: LETTERS PATENT to Matthew Murray Jackson, of Zurich, in the
Republic of Switzerland, Engineer, for the Invention of "IMPROVEMENTS
IN GENERATING STEAM FOR CONDENSING ENGINES."
PROVISIONAL SPECIFICATION left by the said Matthew Murray Jackson
at the Office of the Commissioners of Patents, with his Petition, on the
9th September 1859.
I, MATTHEW MURRAY JACKSON, of Zurich, in the Republic of Switzerland,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE
MENTS IN GENERATING STEAM FOR CONDENSING ENGINES," to be as follows :-
The efficacy of the blast pipe in generating steam as applied to the locomo-
tive engine has been long known; the same principle has been applied to
marine engines working with high pressure. In both cases the whole of the
steam which escapes from the cylinders passes through the blast pipe into the
funnel of the boiler, causing by its pulsatory action a partial vacuum therein,
and thereby greatly increasing, the combustion of the fuel and the production
of steam... Now my Invention consists in applying the principle of the blast
pipe to the boilers of condensing engines, and instead of causing the whole of
the steam which has been generated to pass through the blast pipe into the
chimney, I employ only a portion thereof; and instead of employing a blast
pipe of the usual proportions to the area of the chimney, I employ one of
greatly reduced dimensions. In applying my Invention to marine engines, I

page_text: purpose working a cylinder coupled to the main propeller shaft, but without
any connection with the air pumps or condensing apparatus of the cylinders of
the condensing engines; this cylinder is worked as a non-condensing engine,
and the steam, after having performed its work, escapes through the blast pipe
into the common funnel, thereby greatly increasing the evaporative power of
the boilers; or I purpose making an auxilliary engine for working the air
pumps, feed pumps, & other accessories of the condensing engines, and to
work this engine on the non-condensing principle, causing the steam therefrom
to escape by the blast pipe.
There are various other ways of effecting this object, but the foregoing are
sufficient to illustrate the nature of my Invention.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Matthew Murray Jackson in the Great Seal Patent Office
on the 5th March 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MATTHEW
MURRAY JACKSON, of Zurich, in the Republic of Switzerland, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of September, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Matthew Murray Jackson, Her special licence that I,
the said Matthew Murray Jackson, my executors, administrators, and assigns,
or such others as I, the said Matthew Murray Jackson, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN GENERATING STEAM FOR CONDENSING
ENGINES," upon the condition (amongst others) that I, the said Matthew Murray
Jackson, my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe and ascer-
tain the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.

page_text: NOW KNOW YE, that I, the said Matthew Murray Jackson, 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 (that is to say) :-
The extraordinary evaporative power of the locomotive boiler is chiefly
owing to the action of the blast pipe. The whole of the steam generated by
the boiler, after having performed its work in the cylinders, passes through
this pipe into the chimney, causing by its intermitting discharges a partial
exhaustion of the smoke box, which communicates by the tubes with the fire
box. The consequence is, that the cold air rushes through the spaces between
the fire bars with a velocity proportionate to the difference of pressure between
the atmospheric air and the heated air and gases contained in the smoke box.
The stronger the artificial draught produced by these means, the greater will
be the quantity of fuel which can be burnt on each square foot of the fire-
grate, and consequently the greater will be the quantity of water evaporated
by a boiler of given dimensions. The same principle of obtaining a strong
artificial draught has been applied to the tubular boilers of marine engines,
when these latter have been non-condensing, or what is commonly called high-
pressure engines, the whole of the steam generated by the boiler making its
escape, after having performed its functions in the cylinders, by the orifice of a
pipe into the funnel, in the same manner as in the locomotive engine. Now
my Invention consists in applying the blast pipe to the boilers of condensing
engines, carefully conducted experiments having demonstrated clearly to me
that it is not necessary for obtaining a strong artificial draught, that the whole
of the steam generated should be passed into the chimney, a very greatly
increased evaporation being obtained when only a small portion of the steam
generated is made to pass through a blast pipe of proportionate dimensions.
In applying my Invention therefore to condensing engines, I make a small
cylinder, which is supplied with steam from the same boiler which supplies
the steam for the condensing engine, and I cause the steam, after having
worked the piston of the said small cylinder, to pass through a pipe into the
bottom of the funnel of the boiler, by which means an increased draught and
evaporation from the boiler are effected; the remaining and larger portion of
the steam generated after actuating the piston of the cylinder of the condensing
engine is condensed in the usual manner, forming a vacuum on the side of
the piston opposed to the pressure of the steam. The quantity of steam
necessary for the supply of the small cylinder, in order to produce the requisite
draught, will depend upon the effect desired to be obtained; the greater the
quantity used for the small cylinder, the greater will be. the evaporation

page_text: effected; the quantity will. also depend in some measure upon the
pressure of
steam in the boiler. For marine engines I propose making the admission.of
steam to the small cylinder variable, by means of the link motion or other
expansion gear, and making the small cylinder of such capacity that when the
steam is admitted during three-fourths of the stroke, the quantity of steam
used shall be from one-tenth to one-eighth of the whole quantity generated by
the boiler, but I do not confine myself to this quantity. By this means a
greater or less evaporation will be obtained by admitting more or less steam
into the small cylinder. The pressure of steam proper for working the small
cylinder should not be less than thirty pounds per square inch; and as the
effect is greatly increased by a stronger pressure, I prefer forty pounds or fifty
pounds per square inch. In the case of marine boilers working at a pressure
of twelve or fifteen pounds per square inch, it would be advisable to make a
small. boiler to supply steam of a suitable pressure for the small cylinder.
The funnels of boilers in which the above-described apparatus is to be used
should not be made so large as usual, one-tenth to one-twelfth of the area of
fire-grate being amply sufficient for the area of the funnel; the pipe through
which the steam passes from the small cylinder to the funnel should be about
one-fifteenth of the area of the small cylinder, with an orifice of slightly
diminished area, and which may be from one hundred and twentieth to one
hundred and fiftieth of the area of the funnel; these are proportions which I
prefer, but I do not confine myself to them.
My Invention being of the greatest utility when used for marine engines,
I will proceed to describe some of the ways in which it can be applied.
In the first place, the small cylinder may be used as an independent
supplementary engine, without any connection whatever with the main
engines by which the vessel is propelled, and it might in this case be em-
ployed to work the air pumps, feed, and bilge. pumps, or other accessories,
or it might be applied to work direct on to the. main shaft of a screw pro-
peller in the manner shewn in the Drawing accompanying this Specification.
By this arrangement the air pump is worked direct from the small cylinder,
the surplus power being communicated to the main shaft by a connecting rod
and crank, as hereafter described. The speed at which direct acting engines
working direct on to the screw are worked is always. considerable, and those
shewn in the Drawing are supposed to make seventy-five strokes. per minute,
the discharges of steam from the small cylinder into the funnel would, there-
fore, be one. hundred and fifty per minute, which would be a very favorable
speed for producing the best effect from the blast. Screw engines, on account
of the greater number of strokes they make, are the best adapted for the

page_text: application of the blast pipe; and in the case of existing engines, a small sup-
plementary cylinder might be applied to the main shaft at any convenient
part by means of a crank and connecting rod. In some paddle engines which
make but few strokes per minute, it would be best to apply the small cylinder
as a supplementary engine, working the air pumps or other accessories; in
others, it might work on to the paddle shaft either direct or by gearing with
toothed wheels, so that the blast cylinder should make two strokes while the
main engines made one. The speed which I consider best adapted to the
blast is when the small cylinder makes fifty to eighty strokes per minute..
DESCRIPTION OF THE DRAWING.
Figure 1 is an elevation of steam engines and boilers to which my improve-
ments are applied; Figure 2 is a plan of the same; Figure 3 is an elevation
of the boilers; Figures 4 and 5. are a side view and end view of one of the
marine steam engines; and Figures 6 and 7 are a side view and end view of
the supplementary steam engine. The engines represented consist of two
horizontal cylinders D working direct on the main shaft E of a screw propeller
at seventy-five strokes per minute. The pressure of steam is supposed to be
forty pounds per square inch cut off in the above cylinders at one-third of the
stroke; the steam having performed its work, escapes to the condensor in the
usual way. These cylinders are fitted with pistons, to each of which are
attached two piston rods F, working through two stuffing boxes in the cylinder
covers, and passing one above and the other below the main shaft to a cross
head working in guides carried by the framing. From these cross heads
suitable connecting rods transmit the force exerted by the pistons to the two
outer cranks on the main shaft. In the centre line between the two cylinders,
but on the opposite side of the foundation plate, is a supplementary cylinder G,
which works the air pump H lying opposite to.it, the surplus power from this
cylinder being communicated to the main shaft by a suitable connecting rod
and crank. The admission of steam to this cylinder is variable from one-third
to three-fourths of the stroke, and with the latter admission one-tenth of the
whole quantity required from the boilers is consumed. The steam passes into
this cylinder through a pipe A leading from a branch on the main steam pipe;
after performing its work it escapes through a pipe B into the smoke box,
and is there conducted through a blast pipe C into the bottom part of the
funnel.
I will now state what I consider would be some of the advantages attending
the adoption of my improvements in generating steam for condensing engines.
With a given sized boiler a much greater evaporation can be produced than

page_text: in the ordinary manner; experiments have shewn an increase of from thirty
to forty per cent., and even more, from a certain quantity of grate and heating
surface when acted upon by a small blast pipe of less than the one hundred and
fiftieth part of the area of the funnel. It therefore follows that to produce a
given amount of steam the boilers can be made proportionably less, thereby
effecting a considerable saving in the weight of the boilers, which saving would
increase the tonnage for cargo in a vessel of given dimensions, or with the
same amount of cargo which another vessel of the same size could carry, the
saving in weight of boilers might be made available for fining the lines of
the vessel, by which means less power would be necessary for propelling it
through the water at a given speed, or a greater speed would be obtained with
the same power. It sometimes happens that ordinary marine engine boilers,
under peculiar circumstances, either owing to inferior coal, having to clean
out the fires often, or from the state of the atmosphere, experience difficulty
in keeping up the steam at the proper pressure, and that hard firing has to be
resorted to, by which a great extra amount of fuel is burnt. Now, if such
boilers were provided with a small blast cylinder, they would be able so to
regulate the draught that they would at all times, even with inferior coals,
be able to keep up a regular supply of steam without having recourse to
the extravagant plan of pushing the fires.
Another great advantage to be derived from the saving in weight effected
by my improvements in generating steam is in the case of river boats or
vessels obliged to be built on a limited draft of water, it being evident that
in this case the saving of weight is of the greatest importance, and that engines
working expansively at a pressure of sixty pounds per square inch, condensing
the steam and fitted with a supplementary blast cylinder to work air pumps,
feed and bilge pumps, or other accessories, might be made at least one-third
lighter than usual, enabling the hulls of the vessels to be built with fine water
lines, and causing, as a natural consequence, an increase of speed and diminution
in the consumption of fuel.
It is sometimes the case in India, where wood is used for fuel, and of an
inferior quality for the purpose, that it is almost impossible to make steam at
all, and it is in such cases where the application of the blast pipe from a small
supplementary cylinder would be invaluable.
Having thus stated the nature of my Invention, and described the manner
of performing the same, I wish it to be understood that I do not claim the
application of the principle of the blast pipe, either to marine or any other
class of boilers, the blast pipe having been long applied in connection with
non-condensing or high-pressure engines. I wish it also to be clearly under-

page_text: stood that by the term blast pipe I do not mean a pipe through which a con-
tinuous jet of steam flows direct from the boiler into the chimney without having
previously worked the piston of a cylinder, such small steam pipes having
been many years used in the boilers of marine engines to increase the draught,
but they consume a good deal of steam and do not give a proportionate
increase of effect from the boiler; but I claim as new the production" of a
strong artificial draught in boilers by means of a blast pipe serving as the
eduction pipe of a cylinder, through which only a small portion of the steam
generated by the boiler passes, the remaining and far larger portion of the
steam serving to actuate the piston of the cylinder of a condensing engine,
and being condensed in the usual way after its work is performed.
In witness whereof, I, the said Matthew Murray Jackson, have here-
unto set my hand and seal, this Twenty-third day of February, in the
year of our Lord One thousand eight hundred and sixty.
MATTHEW MURRAY JACKSON. (L.S.)