AxV lUPORlANT DISCOVERY WOOD’S PATENT PUMP. 
67 
quence of the valve occupying a considera- 
ble part of tlie orifice ; and to the extent of 
the difference, is their efficiency necessarily 
diminished. The advantages of the simple 
but important change of position made by 
Messrs. Wood and Quantrille d.re, first, that 
a greater quantity of water can be raised by 
their pump in a given time than by any other 
known to the writer — one of 6 inches bore, 
worked by one man, being capable of raising 
upwards of 76 gallonsof water per minute; 
second, that it is not liable to be chocked, all 
foreign matters that may happen to be sucked 
up with the water having an open and free 
passage from the suction-pipe to the working 
chamber, and thence to tl)e discharge-pipe. 
The portability, or other locomobility, of 
this pump, is another circumstance well de- 
serving attention, It may be shifted or un- 
shifted by one person in a minutes time ; and 
removed by a couple of men from one part 
of a person’s premises, and refixed to another 
in less than a quarter of an hour. Onboard 
of vessels of war, where the decks are often 
required to be cleared of a sudden, with the 
utmost |)Ossible dispatch, this facility of re- 
moval would be found of immense advantage. 
Edit. I\Jech. Mag. C, G. S. 
Southampton, May 6 , 1835 . 
[Mech. Magazine, 1835 . 
HYDRO. PNEUMAl’IC PUMP. 
Sir,— I send you a sketch and description of 
an apparatus for procuring vacuum, which 
1 have lately invented, and which I have call- 
ed the hydro-pneumatic pump. Should you 
deem the communication worthy of notice, 
I should feel obliged by your giving it inser- 
tion in one of your early Numbers; and have 
the honour to remain. Sir, 
Y our most ob edient servant, 
W. II. O. 
March 17, 1835. 
DESCRIPTION. 
The apparatus consists of two stout glass 
cylinders A and B ; the one, A, may be term- 
ed the condenser ; . the other, B, the receiver : 
the former is fixed to the stand G, the latter 
is moveable, for the purpose of experiment, 
d'hese cylinders are fitted with two upright 
brass necks, 1 d ; that of A is furnished with 
a.val ve e, opening upwards into the atmosphere, 
and that of B is bent at a right angle, so as 
to screw at h, on the cross-branch /, from the 
other neck, and thus to form with it an entire 
air-tight tube, which tube has a valve, c, open- 
ing outivards, by a spring or otherwise, into 
the neck I. The cylinder A is farther fur- 
nished with a tube K, for supplying it with wa- 
ter; it passes through the stand G, enters A 
at O, and terminates in F. This tube has a 
cock L, or other similar contrivance, for ad- 
mitting or intercepting the fluid, as may be 
requisite; and near to this in A, as shown by 
the dotted circle M, is another cock for with- 
drawing the water from A, when necessary, 
each of these cocks being both air and water- 
tig'ht. 
The pump is put into operation in the fol- 
lowing manner — the receiver B having been 
previously removed for the sake of experiment,, 
by unscrewing its neck dab, and afterwards 
replaced upon the standing, or rather upon a 
receiver plate attached to it. First, the 
cock L being opened, and that at M shut, 
water is poured or admitted in any other man- 
ner into the pipe K, and flows from it into 
the cylinder A. As it rises it condenses the 
air within A ; the valve e is consequently 
opened, and when it reachesthe height indi- 
cated by the dotted line a; 1 /, it has expelled 
through e nearly all the air which the cylin- 
der contained. 'The valve e havin" again fal- 
len, the cock L is shut so as to cut off the 
supply or water to A. Now this cock, as well 
as that at M, being air tight, and the former 
having, moreover, above it a column of water, 
the level of which; by the laws of fluids, 
corresponds with the line x y, it necessarily 
follows, upon opening the cock at M, so as 
to allow the water in A to escape, and again 
shutting it (taking care, of course, not to 
admit any air from without to pass through it 
into A), that a vacuum will beleft within A ; 
consequently, the air in the receiver B will 
rusli through the cross-tube/, and valve c, 
to restore the equilibrium, and will thus be- 
come rarefied ; this effect will, indeed take 
place as soon as the air in A assumes a less 
density than thatinB, Further, as the air 
which A now contains, and which, it is al- 
most superfluous to observe, possesses the 
same density with that in B, cannot pass back 
to B, for the valve c is now' shut, it also fol- 
lows, that, if the cock L be again opened and 
water readmitted to A, it will be, as before, 
condensed, and ultimately driven out ate; 
and, as a consequence, upon a second time 
opening and shutting the cock at M another 
vacuum will be created in A ; this wdll, like- 
wise, be occupied by the air from B, which 
becomes, of course, still more rarefied ; and 
these operations being repeated, the air in B 
will, at length, be so far exhausted, as to con- 
stitute an almost perfect vacuum. 
1 have not made any reference to the rela- 
tive size ofthe cylinders, this being a point of 
but minor importance. I may, however, ob- 
serve, it is advisable that A should be more 
capacious than B (in proportion, for instance, 
by diameter, of 1|, or l|^to 1) ; because, on the 
withdrawal of the water, the vacuum within 
A, and consequent rarefaction in B, will be 
the greater. On the oth§r hand, it is evident 
