IMPROVEMENTS IN STEAM ENGINES."
Year: 1872

page_text: LETTERS PATENT to Alexander Baumann, of Vauxhall Iron Works,
Wandsworth Road, in the County of Surrey, Engineer, for the
Invention of "IMPROVEMENTS IN STEAM ENGINES."

page_text: piston moves in the direction of the arrow a until it takes the position
shewn in dotted lines at A¹. The steam pressure then enters the passage
O, lifts the valve X, and the slide, having equal pressure acting upon
unequal areas, moves in the direction of the arrow b, which brings about
the position of parts shewn in Figure I., with the piston represented in
dotted lines at A¹. As the slide has brought the passages M and N into
communication the steam describes the way E, K, M, N, and also E, K,
O; the valve therefore remains in its position, and the piston having
equal pressure acting upon unequal areas moves in the direction of the
arrow c until it reaches the position A. It will be seen that by passing
over the passages M and O the piston A has cut off the steam supply to
the back end of the cylinder, and the steam contained therein has
expanded so far that (as the various parts are properly proportioned) the
steam pressure at E and L lifts the valve Y, and acting upon the smaller
area G of the slide overcomes the pressure of the expanding steam, which
acts upon its larger area P, and shifts the valve in the direction of the
arrow d. This produces the position of parts shewn in Figure II., with
the piston at A, and from that moment the same movements as before
described take place.
From the foregoing description of the working of the engine it will
be seen that the steam acts expansively upon the large area D of the
piston and upon the large area P of the valve as soon as the piston has
passed over the passage M. It can therefore be calculated how much
the steam in the back part of the cylinder will have expanded when the
piston is in the position shewn at A, and the proportion between the
steam pressure at E and the pressure of the expanding steam will
determine the proportion between the small area G and the large area P
of the slide, whereby the friction of the slide and the time it takes to
accomplish its stroke must be taken into consideration; similar con-
siderations determine the position of the passage O. The slide starts as
soon as steam enters the passage O, but the piston must at the same
time be supposed to move with an accelerated speed, and the slide has
to travel a certain distance before its movement becomes effective.
Having thus declared and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I would observe in
conclusion that what I consider novel and original, and therefore claim

page_text: mechanism as and for the purposes nerein-before set forth and described,
or any mere modifications thereof.
In witness whereof, I, the said Alexander Baumann, have hereunto
set my hand and seal, this Sixth day of February, in the year of
our Lord One thousand eight hundred and seventy-two.
In witness whereof, I, the said Alexander Baumann, have hereunto
set my hand and seal, this Sixth day of February, in the year of
our Lord One thousand eight hundred and seventy-two.
Witness,
ALEXANDER BAUMANN. (L.S.)
R. S. MORDAUNT VAUGHAN,
54, Chancery Lane.