PUMP. 
52 1 
pipe N, to the spout O, by the descent of the 
plunger, as by its ascent ; and, in each case, 
1 as much water is discharged at O, as tills that 
part of the pump-barrel which the plunger 
moves up and down in. • 
On the top of the pipe O is a close air-ves- 
sel P. When the water is forced up above 
the spout O, it compresses the air in the ves- 
[ sel P; and this air, by the force of its spring 
I acting on the water, causes the water to run 
off by the spout O, in a constant and (very 
nearly) equal stream. 
Whatever the height of the spout O is 
above the surface of the well, the top S, of 
the pipe C, must not be 32 feet above that 
surface ; because if that pipe could be en- 
tirely exhausted of air, the pressure of the 
atmosphere in the well would not force the 
water up the pipe to a greater height than 
32 feet ; and if S is within 24 feet of the sur- 
face of the well, the pump will be so much 
the better. 
As the collar of leathers within the neck 
M, is apt to dry and shrink when the pump 
is not used, and consequently to let air get 
into the pump-barrel, which would stop the 
operation of the atmosphere in the pipe C ; 
collars of old hats might be used instead of 
leathers, as they would not be liable to that 
inconvenience. 
It matters little what the size of the pipe 
N is, through which the water is forced up to 
the spout; but a great deal depends on the 
size of the pump-barrel ; and according to 
the height of the spout O, above the surface 
of the well, the diameter of the bore of the 
barrel should be as follows: 
For 10 feet high the bore should be 6.9 
inches; for 15 feet 5.6; for 20 feet 4.9; for 
£5 feet 4.4 ; for 30 feet 4.0 ; for 35 feet 3.7 ; 
for 40 feet 3.5 ; for 45 feet 3.3; for 50 feet 
3. 1 ; for 55 feet 2.9 ; for 60 feet 2.8 ; for 65 
feet 2.7; for 70 feet 2.6; for 75 feet 2.5; 
for 80 feet 2.5 will do; for S5 feet 2.4; for 
90 feet 2.3 ; for 95 feet 2.2 ; and for 1 00 feet, 
the diameter of the bore should not exceed 
2.1 or 2.2 inches at most. If these propor- 
tions are attended to, a man of common 
strength may raise water 100 feet high by 
one pump, as easily as he could raise it ten 
feet high by anothes. 
In this pump the pipes B and C seem to 
be rather too small ; which will cause the 
water rising in them to have a great deal of 
friction from the quickness of its motion; 
and whoever makes such a pump, will find it 
very difficult to make the leather in the neck 
M water-tight, so that no water shall be for- 
ced out that way when the piston is drawn 
up. 
The hair -rope machine for raising water 
was invented by sieur Vera : 
A (lig. 8), is a wheel four feet over, having 
an axis and a winch ; CC, a hair-rope, near 
one inch diameter ; D, a reservoir to collect 
the water: E, a spout to convey the water 
from the reservoir ; G, the surface of the 
water in the well; I, a pulley under which 
the rope runs, in order to keep it tight. 
When the handle is turned about with a 
considerable velocity, the water which ad- 
heres to the rope, in wells of no great depth, 
is very considerable: the rope thus passes 
through the tubes in D, which, being five or 
ix inches higher than the bottom of the re- 
Vot. II. 
servoir, hinders the water from returning [ 
back into the well, and is conveyed in a con-' 
tinual stream through the spout E. Some of 
the above engines, improved by Mr. Stam- 
ford, have raised a greater quantity of water 
than any person unskilful in hydraulics could 
suppose, m the same time, from such a simple 
contrivance. 
The chain-pump consists of two square, or 
cylindrical barrels, through which a chain 
passes, having a great number of flat pistons, 
or valves, fixed upon it at proper distances. 
This chain passes round a kind of wheel-work, 
fixed at one end of the machine. The teeth 
of this are so contrived as to receive one- 
half of the fiat pistons, which go free of the 
sides of the barrel by near a quarter of an 
inch, and let them fold in, and they take hold 
of the links as they rise. A whole row of 
the pistons, which go free of the sides of 
the barrel by near a quarter of an inch, are 
always lifting when the pump is at work; 
and as this machine is generally worked 
with briskness, they bring up a full bore of 
water in the pump. It is wrought either by 
one or two handles, according to the labour 
required. 
The many fatal accidents which happen to 
ships from the choking of their pumps, makes 
it an important object, in naval affairs, to find 
some machine for freeing ships from water, 
not liable to so dangerous a defect. The 
chain-pump being found least exceptionable in 
this respect, was adopted in the British navy ; 
but the chain-pump itself is not free from im- 
perfections. If the valves are not well fitted 
to the cylinder through which they move, 
much water will fall back ; if they "are well 
fitted, the friction of many valves must be 
considerable, besides the friction of the chain 
round the sprocket-wheels, and that of the 
wheels themselves. To which may be added, 
the great wear of leathers, and the disad- 
vantage which attends the surging and break- 
ing of the chain. The preference, therefore, 
which has been given to chain-pumps over 
those which work by the pressure of the at- 
mosphere, must have arisen from one circum- 
stance, that they have been found less liable 
to choke. 
In point of friction, of coolness, and of 
cheapness, the sucking-pump has so evidently 
the advantage over the chain-pump, that it 
will not fail to gain the preference, whenever 
it shall be no longer liable to be choked with 
gravel and with chips. 
Buchanan’s pump, which, like the common 
pump, acts by the pressure of the atmosphere, 
is not liable to the defects incident to other 
pumps upon that principle, being essentially 
different from any now in use. 
The principal object of its invention was 
to remove the imperfection of its choking. 
In attaining this important end, a variety 
of collateral advantages have also been pro- 
duced, which enhance its utility. 
The points in which it differs essentially 
from the common pump, and bv which it 
excels, are, that it discharges the water be- 
low the piston, and has its valves lying near 
each other. 
The advantages of this arrangement are, 
that the sand or other matter, which may be 
in the water, is discharged without injuring 
the barrel or the piston-leathers; so that be- 
sides avoiding unnecessary wear and tear, I 
3 U 
the power of the pump is preserved, and not 
a pt to be diminished or destroyed in moments 
of danger, as is often the case with the com- 
mon and chain pumps: that the valves are 
not confined to any particular dimensions, 
but may be made capable of discharging 
every thing that can rise in the suction- 
piece, without danger of being choked: that 
if there should happen upon any occasion to 
be an obstruction m the valves, they are both 
within the reach of a person’s hand, and may 
be cleared at once, without the disjunction of 
any part of the pump : and that the pump is 
rendered capable of being instantaneously 
converted into an engine for extinguishing 
(ire. Besides, it occupies very little space in 
the hold, and thus saves room tor stowage. 
But this pump is not confined to nautical 
uses alone ; its adaptation extends to the 
raising of water in all situations, and with pe- 
culiar advantage where it happens to be mixed 
with sand or substances which destroy other 
pumps, as, for instance, in alum- works, in 
mines, in quarries, or in the clearing of foun- 
dations; and in its double capacity it will 
be very convenient in gardens, bleaching- 
grounds, in stable and farm yards, and in all 
manufactories, or other places, where there 
are a necessity for raising water and the risk 
of fire.' 
With all these advantages, it is a simple 
and durable pump, and may be made either 
of metal or wood at a moderate expence. 
Fig. 9, is a vertical section of the pump, as 
made of metal, in which A is the suction- 
piece, B the inner valve, C the outer valve. 
The valves are of the kind called clack- 
valves. Their hinges are generally made of 
metal, as being more durable than leather. 
D is the working-barrel, E the piston, and 
G the spout. 
The following parts are necessary only 
when the pump is intended to act as a fire- 
engine: 
H an air-vessel, which is screwed like a 
hpse-pipe, that it may, at pleasure, the more 
readily be fixed or unfixed. 
There is a perforated stopple for the spout, 
made for receiving such pipes as are com- 
mon to fire-engines. It is oval and tapered, 
and being introduced transversely, upon beina 
pulled back becomes immediately tfoht. 
These parts being provided, all that is ne- 
cessary to make the pump act as a fire-em, 
gine after having been used as a suckiug- 
puinp, is to plug up the spout with the stop- 
ple. 
No particular mode being essential in the 
working of this pump, it may, according to 
choice- 'or circumstances, be wrought ail 
the methods practised with the common 
pump. Jn many cases, however, it may be 
advantageous to have two of them ‘so con- 
nected, as to have an alternate motion ; in 
which case, one air-vessel, and even one 
suction-piece, might serve both. 
Its principles admit of various modifica- 
tions; but as what is already mentioned may 
he sufficient to indicate its" superiority over 
the common and chain pumps, and the ad- 
vantages likely to result from its general use 
a further detail is unnecessary. 
To this we may add, that the testimonies 
of several navigators confirm in the fullest 
manner, the hopes that were conceived of its 
