IMPROVEMENTS IN STEAM ENGINES
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ELIJAH
GALLOWAY, of Southampton Buildings, Chancery Lane, in the County of
Middlesex, Civil Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Tenth day of March,
One thousand eight hundred and fifty-one, in the fourteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Elijah Galloway, my exors, adiiors, and assigns, Her especial license, full
power, sole privilege and authority, that I, the said Elijah Galloway, my exors,
adñiors, and assigns, or such others as I, the said Elijah Galloway, my exors,
adiiors, 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, and in the Islands of Jersey, Guernsey,
Alderney, Sark, and Man, and also in all Her said Majesty's Colonies and
Plantations abroad, my Invention of "IMPROVEMENTS IN STEAM ENGINES;" in
which said Letters Patent is contained a proviso that I, the said Elijah
Galloway, shall cause a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, by an instrument in
writing under my hand and seal, to be inrolled in Her said Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said in part recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.

page_text: motion by the steam engine through the arc A, D, gives motion to the rod d,
which is attached by a pin joint at one end to the beam c, and at the other end
by a pin joint to the rod d', which at one end is attached to the crank pin of the
crank b. The other end of the rod d' is attached by a pin joint to the link e,.
which, at its other end, moves on an axis fixed to the framing of the engine.
The effect of this arrangement will be, that by the movement of the piston
through one third of the length of the stroke (whether in the up stroke or in
the down stroke), the crank pin will be moved through an arc of nearly one
half of the length to that through which it will be moved by the complete up
or down stroke of the engine; and the remainder of the motion of the crank
pin will require the piston to move through the remainder of its stroke; that
is, through a space of about two thirds the length of movement of the piston.
This will readily be understood by reference to the Drawing. The beam or
other instrument, in moving from A to B, which represents one third of the
up or down stroke of the piston, causes the crank pin to move through the
space A to B on the circle described by the crank pin, or nearly a quarter of
a circle, during which time the steam is supposed to be full on, and to be cut
off when it comes to B; and in the movement from B to C the piston will be
pressed on by a less and less effort of steam, and the crank pin will only be
moved from B¹ to C', although the piston will have passed a like space, that
is, about one third of its stroke; and the piston, in completing the stroke from
C to D, will again pass through one third of the stroke whilst the crank pin
will be caused to pass from C' to D', and the beam or other instrument put in
motion by a double-acting steam engine. In passing back from D to C the
crank pin will pass from D¹ to E, a distance equal to that between A¹, B', and
so on, performing, in like manner, for the one stroke of the piston, what has
been described in respect to the other stroke or movement of the piston from
one end to the other end of the cylinder.
I am aware that Watt proposed to equalize the effect of the pressure of
expanding steam on a piston in respect to the load of a single-acting steam
engine; that is, an engine where the steam is only admitted on one side of
the piston. I do not, therefore, claim the same, but confine my Invention to
double-acting steam engines; that is, where the steam alternately acts on
either side of the piston. It will be evident that like benefits will not be
obtained when reversing the engine. If necessary, on accasions it will be
desirable to admit more steam.
Having thus described the nature of my Invention, and the manner of per-
forming the same, I would remark that I do not confine myself to the precise
mechanism shown, as the same may be varied without departing from my

page_text: Invention, so long as the peculiar character of my Invention be retained, and
a suitable arrangement of mechanism is interposed between the piston of a
double-acting engine and the load put in motion thereby, to cause the load to
be moved through a greater space for a given motion of the piston when acted
on by the greatest amount of pressure of the steam than the load will be
moved through by the piston passing through a like space when pressed on by
expanding steam, and consequently offering a less amount of pressure. And
I would have it understood, that what I claim is, the employment of mecha-
nical means, interposed between the piston and the load of a double-acting
steam engine, to compensate for the decreasing effort of expanding steam, and
thus, as nearly as may be, obtain a practical uniformity of the effort in respect
to the load.
In witness whereof, I, the said Elijah Galloway, have hereunto set my
hand and seal, this Eleventh day of March, One thousand eight