AN IMPROVEMENT IN WORKING STEAM ENGINES
Year: 1854

page_text: LETTERS PATENT to Frederic Martini, of Elberfeld, in the Kingdom
of Prussia, residing at 1 & 2, Mumford Court, Milk Street, City of
London, for the Invention of "AN IMPROVEMENT IN WORKING STEAM
ENGINES."
Sealed the 8th August 1854, and dated the 15th June 1854.
PROVISIONAL SPECIFICATION left by the said Frederic Martini at the
Office of the Commissioners of Patents, with his Petition, on the 15th
June 1854.
I, FREDERIC MARTINI, of Elberfeld, in the Kingdom of Prussia, residing
1 & 2, Mumford Court, Milk Street, City of London, do hereby declare the
nature of the said Invention for "AN IMPROVEMENT IN WORKING STEAM ENGINES"
to be as follows:-
My Invention consists in surrounding the cilinders of steam engines by
mantles, and filling the intermediate space between cilinder and mantle with
steam of a considerable higher pressure, accordingly of a higher temperature,
than the one has used to set the engine going. And in order that my Invention
may be most fully understood and readily carried into effect, I will proceed to
describe the means pursued by me.
It is well known that there is a considerable condensation taking place in

page_text: the cilinders of steam engines, and that the quantity of water actually evapo-
rated is never in accordance with its calculated effect, the quantity consumed
being always so much larger as it ought to be to produce a given power.
1
have reason to believe the non-accordance of calculated and really con-
sumed steam is solely owing to the before-mentioned condensation. The sum
of latent and free heat contained in steam, of whatever tension or pressure it
may be, is always 560; supposed that of boiling water to be a 100, it is evident
therefore that saturated steam cannot lose one atoin of its heat without being
partly condensed: I am well aware that many expedients have been practized
to counteract the great tendency which steam has to give off part of its heat
to surrounding objects; for instance, it has been tried to surround steam
cilinders by mantles, letting the exhaust steam pass through the intermediate
space; or, instead of this, also, steam directly from the boiler, before its
entering the cilinder, or to apply overheated steam; but, as to my knowledge,
none of all these expedients have been crowned by even an aproximate success.
This is not surprising, because the condensation would go on just as well if
by some means or another the exterior surface of cilinders could be kept at a
temperature exactly like that the steam has by which the engine is worked,
and that in reason of the thin film of water which covers the inside of the
cilinders. This small quantity of water may be considered as the principal
agent to transfer the heat from steam to the sides of the cilinder cach time
fresh steam is blowing into the last. The water present takes up some part of
its heat, producing a corresponding condensation, and acquires the temperature
of the entered steam, and each time the stroke changes the water heated above
212° F. will lose suddenly all surplus of heat, that is to say, all heat above
212° F., which becomes latent in form of steam, in correspondance with a well-
known physical laid. This water cooled down to 212° F. will act in a similar
manner as before, on a new portion of steam, &, &. To counteract this
injurious condensation, I make use of exactly the same principle which pro-
duces it, that is to say, I awail myself of the great specific heat steam possesses,
and of its propensity to give off very rapidly part of its heat in condensing
itself. To carry out my Invention, I surround the cilinder of any engine by a
mantle, as is well understood, and fill the intermediate space with steam of a
considerable higher pressure, accordingly also of a much higher temperature,
as the steam has which is used to work the engine. For instance, working
an engine with steam of 3 atmospheres pressure, I would prefer to fill the
space between mantle and cilinder with steam of no lesser than 5 atmospheres
pressure; but I want to have it understood that I do not confine myself to any
particular steam pressure, provided the steam surrounding the cilinder has a

page_text: higher pressure than the one used to set the engine in motion. Hot air or
over-heated steam might be used, but what I prefer to use is steam of a higher
pressure. I connect a smali tap to the bottom of the intermediate space in
question to let out the condensed water. The steam necessary to carry out
this operation I prefer to generate in a small but strong separate boiler, which
ought not to have more than 1½ foot diameter by 3 feet length, for an engine
of a hundred horses power.
Having thus described the nature of my Invention, and the manner of per-
forming the same, I would have it understood that I do not confine myself to
the details described, as long as the peculiar character of my Invention is
retained. I do not claim the introduction of stean between mantle and
cilinder; but what I claim is, the surrounding and heating of steam cilinders
by saturated steam of a higher temperature and pressure than the one has
which is used to work the engine.