NEW AND USEFUL IMPROVEMENTS IN STEAM ENGINES
Year: 1875

page_text: LETTERS PATENT to George Basil Dixwell, of the State of Massa-
chusetts, of the Republic of the United States of America, for the
Invention of "NEW AND USEFUL IMPROVEMENTS IN STEAM ENGINES."
COMPLETE SPECIFICATION filed by the said George Basil Dixwell at
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 20th August 1875, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
BASIL DIXWELL, of the State of Massachusetts, of the Republic of the
United States of America, send greeting.
WHEREAS I am in possession of an Invention of "NEW AND USEFUĻ
IMPROVEMENTS IN STEAM ENGINES," and have petitioned Her Majesty to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I am
the first and true Inventor thereof.
NOW KNOW YE, that I, the said George Basil Dixwell, do hereby
declare that the following Complete Specification, under my hand and

page_text: 17
seal, fully describes and ascertains the nature of the said Invention, and
‹ in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawings making
part of this my Specification:-
My Invention relates to improvements in steam or vapor engines
whereby the cylinder condensation arising from the alternate cooling
and heating of the piston, its rod, and the interior surfaces of the
cylinder (as well as those of the intermediate receiver in some forms of
compound engines) may be either prevented or greatly diminished. This
cylinder condensation. becomes greater as the measure of expansion is
increased. The steam jacket diminishes it to so small an extent that
it may still be said to be the chief obstacle to the economical working
of engines.
1
The difficulty appears to arise in the following manner, namely:-
At the first stroke of the piston an amount of heat equivalent to
the work done during expansion, and equivalent to radiation, is
abstracted from the steam in the cylinder, and thus forms a quantity
of dew or mist, which dew or mist evaporates in part during expan-
sion and the return stroke, and chills the interior metallic surfaces.
These upon the next stroke condense an amount of steam equal to that
which has just been evaporated, thus reproducing in the cylinder the
mist or dew formed during the first stroke, or such portion of the said
mist as was re-evaporated; but now upon this second stroke also occurs a
fresh condensation to balance radiation and the heat converted into
work, so that upon this second stroke there is more dew or mist than
there was upon the first. This is re-evaporated and chills the interior
metallic surfaces more than they were chilled during the first stroke,
and so there is a greater condensation when the steam enters upon the
third stroke, and so on. The action is cumulative and can only reach its
limit when the steam condensed up to the point of cut off equals the
re-evaporation plus that which is condensed during a single stroke to
balance radiation and the 'heat converted into work, that is to say, the
spray or mist present in the cylinder at the point of cut-off is partly
re-evaporated and partly passed on as spray suspended throughout the
whole body of steam, and the spray or mist thus passed over must be
the precise equivalent of the refrigeration which occurs in or reaches
the interior of the cylinder up to the point of cut-off from all causes
apart from re-evaporation.
1

page_text: Experiment has shown that the refrigeration arising from re-evapora-
tion (caused by the cumulative action of the metal) is (in medium and
large engines), about five times as great as the refrigeration arising from
all other causes, and still more in small engines. The object then is to
prevent this re-evaporation, and if the whole of the interior surfaces
could be covered with a non-conducting substance the end might be
reached in that way.
The parts not subjected to attrition may be so covered; and with
respect to other parts I avail myself of that property of metals, whereby
at certain elevated temperatures they repel minute quantities of water;
and this they do at temperatures decidedly below the 400° F. to which
it has been found safe to subject the working parts of engines. Water
in perceptible drops is thus repelled by iron at 386° F., and by copper at.
335° F., and an imperceptible mist is repelled at lower temperatures.
Ether, alcohol or bisulphide of carbon is repelled at much lower tem-
peratures than water. I effect my purpose then by applying a non-
conducting substance to the top and bottom of the piston, and also to
the internal surfaces of the top and bottom, or ends of the cylinder, and
by heating the sides of the cylinder sufficiently to cause them to repel the
mist which is formed by the conversion of heat into work and by radia-
tion. This cannot be effected by an ordinary steam jacket, and I there-
fore make use of a jacket of hot air, or one of superheated steam. I
prefer to derive the hot air from a separate furnace urged by a system
of steam jets, which being increased or diminished by one or more
regulating throttle valves, will increase or diminish the supply of hot
air to the jacket, but any other proper means of heating and regulating
the heat of the jacket may be used.
- The hot air jacket should not generally surround the valve parts,
but be sufficiently withdrawn from them to avoid heating the valves by
conduction.
The interior surfaces are at every stroke subjected to refrigerating
causes, and experiment has shown that they will not become heated
materially beyond the temperature of the steam which is in contact with
them. A thin film of the metal parts with its heat to the adjacent
steam with immense rapidity, so that if the metal should become over-
heated the steam will attain nearly the same temperature. I keep
watch-then over the heat of the cylinder- by keeping watch over that

page_text: through the jacket E applied to such cylinder. Near. the lower end of
the thermometer there passes out of it a wire which we will call wire A³,
and which proceeds to the polc N of a galvanic battery F and serves to
electrically connect this pole with the wire next above, which we will
call wire B¹; so long as the mercury is above the said wire B¹ and also
with a wire (which we will call wire C', and which passes out through
the top of the thermometer) whenever the mercury touches it. This
wire C¹ is passed out through the top of the thermometer, or screws
therein in such a manner that it (the wire) can be raised or depressed at
pleasure and be fixed at any desired point, say, for instance, at 400° F.
This wire C' should be connected with an electric bell or alarum
apparatus A', and through such with the pole S of the battery, so that
whenever the mercury touches the wire a current passing through
wire A from the pole N, and round through wire C' and the bell to the
pole S of the battery, would give the alarm and. notify the engineer to
diminish the heat in the jacket, as hereafter described.
The wire B' passes to the electro-magnet D', and thence to the pole S
of the battery in such a manner that as long as the mercury is above B¹
a current flows from the pole N through A', through the mercury,
through B', over the electro-magnet D', and thence to the pole S; thus,
as long as the mercury is above B', the electro-magnet is a magnet.
or is attractive, and holds its armature in contact, and through the
lever which proceeds from the armature it holds out of the cup of
mercury G the wire H, which forms a portion of the circuit of another
electric bell or alarm apparatus K; thus, so long as the mercury is above
the wire B¹, the circuit of the bell K is broken, but as soon as the
mercury descends below the wire B' the current from A to B¹ is broken,
the electro-magnet D¹ ceases to attract the armature, and the armature
being overweighted by the opposite end of the lever, or pulled on by a
spring S³, ascends, the wire H descends into the cup of mercury G, the
circuit of the electric bell K is complete, the bell rings and warns the
engineer that a previously selected minimum temperature, say, for
instance, 370° F. has been reached, and that it is time to increase the
heat in the jacket as described. It should have been mentioned that the
wire B¹ is supposed to pierce the thermometer at the point marking the
said temperature of 370° F.
C is the furnace for supplying hot air for the jacket; E, N¹, and O, are
nines admitting steam iets from the boiler B. and they may or should be:

page_text: furnished with throttle valves or cocks P and Q, by means-of-which
valves or cocks the flow of hot air through the pipe R and the branch
pipes S¹ and T, and through the jacket E, and thence through the pipe U
into the feed water vessel 02 is governed.
Now let us imagine the engine to be set at work, and that the hot-air
furnace is acting too energetically, the mercury in the thermometer will
rise until it touches the wire C³, and will thus complete the circuit with
the wire A¹, and the interposed electric bell will give the needed alarm,
and the engineer will diminish the action of the furnace by partially
closing the throttle valves P and Q. If these be closed too much the
beat in the cylinder will be diminished, the mercury will descend below
the wire B¹, the circuit passing between B¹ and A' around the electro-
magnet D¹ is cut, and D¹ then ceases to attract its armature; the wire H
descends into the cup of mercury G, completes the circuit, and the bell K
gives the alarm, and notifies the engineer to increase the action of the
furnace by partially opening the throttle valves P and Q.

page_text: render its inner surface repellant of mist, as described, I claim the heat
non-conductors applied to the piston head and to the ends of the cylinder,
as set forth.
I claim in combination with the steam engine cylinder and its hot
air jacket or means of heating the cylinder, as and for the purpose
specified, a thermometer and the electrical alarm apparatus, or apparatuses
substantially as described, applied thereto to indicate the extremes of
temperature to be maintained in the cylinder to prevent the formation
of mist in said cylinder as or under circumstances as stated.
In witness whereof, I, the said George Basil Dixwell, have hereunto
set my hand and seal, this Twenty-eighth day of May, A.D. 1875..
GEORGE BASIL DIXWELL. (L.S.)