254 
Description of a Plunger Pump, 
[Aug. 
fitted so as to enclose these openings, have each a valve, opening inwards, and 
opposite the valves in the trunk ; the upper tampion of the plunger box has a hole 
cut through it, of sufficient diameter to admit the plunger and its collar freely ; 
say the plunger is 5 inches diameter ; which, when the collar is on, is encreasedto 
H ; then the hole in the upper tampion should be at least 54 , The collar is 
made of good Europe pump leather, and cut so as to form, when bent round, the 
frustum of a cone ; the smallest diameter of which must be in the clear, just the 
size of the plunger. The two parts of the leather which meet to form the collar, 
must be chamfired off so as to overlap each other, but must not be sewn together ; 
— the base of the frustum may be hammered out into somewhat of a trumpet 
shape, to receive the nails which attach it to a block 2 , which block is screwed 
to the upper tampion of the plunger box, so as to allow the collar to protrude 
through the hole before mentioned ; round the margin of this hole is placed a ring 
of loosely twisted hemp, which, when the block is screwed down upon it, prevents 
the water escaping between them. To work this Pump to the greatest advantage, 
it should be immersed in the water, to just above the plunger boxes, otherwise the 
collars, being fitted very slack, (to prevent friction,) would admit the air, when 
the plunger is drawn up ; but when this part is covered with water, this slack- 
ness, which is highly advantageous, as reducing friction, is not at all calculated 
to admit of the escape of any water when the plunger descends ; for then the pres- 
sure of the fluid shuts the outer valve, opens one of those into the trunk, and at 
the same time presses the lower part of the collar, (which, it must be recollected, 
instead of being sewn together, merely overlaps, as before mentioned, with two 
chamfired edges, was to allow of its expanding and contraction,) closely round the 
plunger. 
As 1 am but too apt to make mistakes in my calculations, I will give you the 
data from which I have ascertained the quantity of water the Pump will deliver in 
a given time. It is placed in a tank, obliquely, the jet pipe leading into a reservoir 
of masonry ; the perpendicular height from the surface of the water to the jet pipe 
is 8 feet 5 inches ; the reservoir, which is cylindrical, is 6 feet 3 inches diameter, 
and 2 feet 3 inches deep. Two men working the Pump will fill this reservoir in 
thirteen minutes. Now, unless 1 am “ out in my reckoning,” this reservoir will 
contain 69 cubic feet, which, at 231 inches to the gallon, is equal to 516 gallons. 
I have compared this with a common lift pump, (an old ship’s,) which is placed in 
a well of masonry, for raising water into an aqueduct ; this well is 5 feet diameter : 
four men, constantly pumping, lowered the water 2 feet 1 inch in 30 minutes; 
mean height of the column 1 1 feet f of an inch ; although there were four men : 
I should say that three would be sufficient, hut not less. 
From the above, I make out that in 30 minutes 
Ihree men, with the Lift Pump, will raise 306 gallons of water. 
Two ditto with Plunger Pump, 1190 ditto ditto. 
dunnage deals at 3, 
shiubin, 
iron hoops, 
carpenter employed 47 days, 
at 8 Rs. per mensem, 
Europe purnp leather. 
Screws and nails, 
Saul plank for beam. 
Two spars for plunger. 
9 
10 
10 
0 
0 
0 
13 1 
2 
2 
2 
2 
0 
0 
0 
0 
Rs. 50 1 
The cost, as exhibited in the margin, 
might be reduced ; as the ends of planks, 
of 3 feet long, might be substituted for 
the shinbin ; and the man who made it 
idled away more than half his time, from 
having other matters to attend to. 
Your’s faithfully. 
Diamond Harbour , "1 
August 23, 1830. J 
C. Cowjles. 
. Remarks by the Editor . 
Vi 1 . to ' vhom we are indebted for the above letter, thinking with our- 
IvSc f* ,° dressing up” could improve it, we have given it exactly in the 
' s> w we hope, may be induced to favour us with some further 
ti 1C * lc ? ns °[! use ^ u i subjects. We have yet failed to draw from practical 
, , ie nu >u >ei of communications which we had expected at our outset to see, 
n fforinr. o . We k ^° W u ? ust be ca P abl e of furnishing. Some are deterred from 
a flic - n r ^,? eS lon |’ deeming them of little value, and less interest : others from 
disinclination or fancied inability to write any thing that shall be worth reading. 
pionsf ancf the hoLT? n C ?£ t0 Uppei | part of the P ,un £ er box, over the upper tain- 
to fit the tr um net month «??i» b c>C i? Ule ! a . r ? e F than those m the tampions, and are cut 
trumpet mouth of the collar, which is closely nailed to it. 
