MECHANICS. 
f«cking.pump; and that, when'the pifton E is deprefled, 
it will force the water between it and the valve B, through 
the valve C, and make it iflue at G. The points of dif¬ 
ference between this pump and thofe of the common 
form, are, that it difcharges the water below the pifton, 
and has its valves lying near each other. Hence the fand 
or mud which may be in the water, is difcharged without 
injuring the barrel or the pifton-leathers; and, as the valves 
.B, C, may be of any fize, they will tranfmit, without 
being choked, any rubbilh which may rife in the fuftion- 
barrels. If any obftruCtion fhould happen to the valves, 
they are within the reach of the workman’s hand, and 
may be cleared without taking the pump to pieces. This 
fimple machine may be.quickly converted into a fire-en¬ 
gine, by adding the air-veflel H, which is fcrewed like a 
hofe-pipe, and by fixing in the fpout G a perforated 
Hopple fitted to receive fucli pipes as are employed in 
fire-engines. When thefe additions are made, the water, 
as in the cafe of the forcing-pump, will be driven into the 
air-veflel H, and repelled through the perforated ftoppie 
G, by the elafticity of the included air. 
The ingenious Mr. Benjamin Martin invented a fliip’s 
pump with two barrels drawing from one fu&ion-pump, 
(b as to raife a contfant ftream. This has much merit, 
and aCts extremely wells the conflant ftream raifed by 
the alternate action of the two barrels upon one pipe pro¬ 
duces an advantage that was fhown by experiment; for 
the water not only riles while the pifton rifes, but conti¬ 
nues to do fo even after the pifton begins to defeend ; 
and therefore the pump was found to deliver more water 
than was expected from calculation of the contents of 
the barrel, and the number of ftrokes made. To account 
for this, it mull be confidered that, as this pump has both 
its large piftons working (alternately afeending and de- 
feending) at the fame time, there mult be produced a 
conftant rifing column of water in the pipe, whole velo¬ 
city through a bore of five inches, to fupply the barrels 
of twelve inches diameter each, muft be fo great, that it 
cannot be checked or ftopped at once, or upon the firft 
defeent of the pifton ; and therefore a furplus of water is 
produced. Notwithftanding thefe advantages of Mr. Mar¬ 
tin’s pump, it has objections which are lerious obftacles 
to its ufe on-board (hips, though in other fituations it is a 
good machine: thefe are, the fliortnefs of its ftroke, which 
renders it very fatiguing for men to work for a long 
time ; and another more lerious objection, that the leathers 
would, in general, remain dry, and thus become liable to 
harden and grow ftifF, fo as to break into holes when 
ufed at firft, before they become foaked ; and to fill the 
ciftern firft with water would be very troublefome. 
The hand-pumps now very commonly ufed in the navy 
are the invention of Mr. Walter Taylor, of Southampton. 
They are deferibed by Mr. Adams (LeCt. on Nat. Phil, 
vol. iii.) in the following terms: “ Every friend of man¬ 
kind muft rejoice, that the accidents to which (hips that 
fpring a leak at fea were liable from the imperfections of 
the chain-pump, are happily removed by this ingenious 
contrivance. It fee ms rather furprifing that the common 
pump, whofe effeCts are fo well known, Ihould have re¬ 
mained for centuries inadequate to the purpofes of the 
navy. The mechanifm adapted by Mr. Taylor is fo im¬ 
portant, and, in various particulars, fo different from what 
is in general applied to the common pump, that it may 
with great propriety be confidered as a new invention al¬ 
together. Thefe pumps have been in general ufe in the 
navy for five or fix years; and they have anfwered every 
expectation he firft formed, though he has made many 
improvements on them during that period. The figures 
will afford a general idea of thefe pumps ; they were co¬ 
pied from drawings which were kindly communicated to 
me for that purpofe by Mr. Taylor. Fig. 86. is a feCtion 
of one of thefe pumps, of a fimple conftruCtion. The 
pifton is reprefented as defeending in a chamber properly 
adapted to it. At a and b we have a view of Mr. Tay¬ 
lor’s pendulum-valves; which, from their form, difengage 
V«l. XIV. No. ion. 
757 
themfelves from chips, gravel, fand, See. The pifton is 
alfo fo contrived, that no chips, gravel, or fand, can get 
between the leather and lower part of the pifton ; to both 
which defects the former conftruCtions were liable. This 
pump works with one pifton-rod ; and at fig. 87 is a pump 
working with two pifton-rods; the one rifing as the other 
falls: in thefe figures the rods are fuppofed to be worked 
by levers. By a judicious application of ropes, to be car¬ 
ried on either deck, Mr. Taylor is enabled, where men 
are plenty, as in a man of war, to raife any quantity of 
water. The drawing is taken from a pump with a feven- 
inch bore, and heaves one ton per minute twenty-four feet 
high, with ten men, five only working at a time. One is 
now cor.ftruCting by Mr. Taylor to heave five tons per 
minute twenty-four feet high. The pumps are alfo fa 
conftruCted that a copper pump may be taken out of the 
wooden cafe, in order, when necefiity requires, to make 
two pumps for feparate work.” 
The lateft improvements that we have heard of in 
hand-pumps for (hips are by Capt. Jekyl, R. N. This 
gentleman has invented an addition ro the pump of an 
air-veflel, and ftuffing-box for the rod to pafs through, 
by which it will raife the water to a greater height than 
the head of the pump; and, a hofe being attached to the 
pump-fpout by very fimple means, the water is conveyed 
to any defired part of the Ibip, and thrown in a jet through 
a nofe-pipe with great force, to extinguifh fire, if fuch a 
calamity fhould befal a fhip ; and thus the pump is ren¬ 
dered of twofold fervice. The idea of converting the 
pump to a fire-engine is not new, having been attempted 
in many different ways by forcing-pumps; but thefe, 
having pipes proceeding from the lower part of the bar¬ 
rels and valves, which are not very accefiible, are always 
liable to choke up by obltructions, and have not fucceeded 
in general ufe. The air-veflel has always been in the 
way, if made of a fufficient fize to anfwer the purpofe of 
equalifing the ftream. Capt. Jekyll has obviated thefe 
objections, and, without altering the material parts of the 
hand-pump, has rendered it as complete a fire-engine as 
can be wifhed. When it is ufed as a fire-engine, a hofe 
is fixed on by link-joints, and keys or wedges ; the nozzle 
is fixed to the pump by four fcrevv-bolts going through 
the thicknefs of the pump, and it is fixed in fuch a di¬ 
rection as will moll conveniently lead to a receiver which 
unites the holes from all three of the fliip’s pumps. 
The dilpofition of the three hand-pumps in a (hip’s well 
renders their connection with a common receiver very 
convenient to bring all the water into one ftream, which 
will then be very powerful, and more capable of extin- 
guifhing a fire than any moveable engine. Two hand- 
pumps are always placed on the ttarboard fide of the 
main-maft, in the well; and, one of them being the cif- 
tern-pump ufed for wafhing decks, its foot ftands in a 
fmall ciftern fixed upon the ltep of the main-maft, and 
fupplied with water by a pipe through the (hip’s fide, with 
a cock to admit it at pleafure; there is one pump on the 
larboard fide of the mart ; three feparate hofes being united 
with each of the pumps by a link joint at one end, and 
with three necks of a receiver by fimilar joints at the 
other, brings all the water into one; and a hofe, being 
joined by a link-joint to the oppofite end of the receiver, 
conveys the whole water to any part of the fliip. The 
receiver has the three nozzles at one end made in a di¬ 
vergent direction, agreeably to the directions in which 
the hofes come from the three different pumps ; and a 
valve is placed withinfide, before each hofe, to open in¬ 
wards, in order that the receiver may be ufed for one or 
two pumps, whillt the others are repairing or gettiny 
ready, or that, if any of the hofes burft, the water may 
not elcape from the receiver at that nozzle. There are 
two handles fixed to the receiver, to lift and carry it, as 
it is to be moveable; and, when in ufe, is propofed to be 
laid on the grating of the main hatchway, as the moft 
central fituation, from which the hole may be carried in 
any direction, A branch-pipe, or jet, is lcrewed at the 
9 G end 
