1830 .] 
On the Rent and Produce of Land. 
2o5 
But the former should consider, that what appears familiar and trivial to them, is 
to many not known at all ; and the more practical it be, the less likely it is to he 
known to any. To the latter we would say, that if a man have useful or interest- 
ing information to communicate, the plainer and simpler his style is, the better. 
With regard to Captain Cowles' Pump, we think it very ingenious, and though 
not exactly the same as Professor Robison’s plunger, mentioned in our first 
volume, in all its details, it is yet on the same principle. But unfortunately — and 
we would suggest this for the ingenious inventor’s consideration — it is altogether 
different in the manner in which the labour is applied, — the particular feature 
which constitutes the great excellence of Professor Robison’s pump. Thus, in 
the present machine, the oscillating beam is alternately pulled down on each side 
by the rope attached, consequently the labourer applies no force, beyond that which 
is derived from the exercise of the muscles of the arm. Now, in Professor Robi- 
son’s pump, the beam is worked by the man’s weight, the muscles of his body 
being used, (and this is the most effective exertion,) to raise himself up again, 
after, by descending, he has carried down with him the descending arm of the 
beam. Thus there is a double force applied, or an equal one , with half the exer- 
tion, which may consequently last twice as long. But this is not all. For, as 
before observed, it is precisely this action of the muscles which enables a man to 
perform most work ; — so that whether, as in the present pump, he pull down an 
oscillating beam by a rope, or turn a winch, or work a pump handle, in none of 
these operations is the same quantity of work performed, with the same expendi- 
ture of animal power, as when a man’s exertions are confined to walking along an 
oscillating beam, or ascending a ladder, and descending in a box fastened to a rope, 
which passing over a pulley, raises the weight required ; or lastly, walking on the 
internal or external periphery of a large wheel. This fact is well known, having 
been repeatedly ascertained by experiment ; the actual amount of the superiority 
appearing to he a little doubtful. If we are to take Professor Robison’s estimate 
of its value, it ought at once to supersede every other mode of applying human 
or animal labour ; and so favourable are even the lowest estimates, that we think 
it well worth the attention of practical men. In the pump above described, a fair 
opportunity offers of trying it. A bamboo stage could be affixed at a very trifling 
expense to the beam, and a man employed to walk backwards and forwards ; the 
result, we really think, will be found such as could not have been anticipated. 
The particulars given by Captain Cowles enable us to compare the performance 
of this pump, worked as it is at present, with that of other machines for raising 
water described in the Gleanings 1 . It appears that two men working at it, raise 
69 cubic feet of water, 8 feet 5 inches in 13 minutes. This is equal to 22,34 cubic- 
feet, raised 1 foot high in one minute by each man. This is a little more than 
one~.fourth of what Professor Robison’s feeble old man effected on the walking beam, 
which was 80,5 cubic feet. It is but 4 trifle more than one-fifth of what his stout 
young man,” loaded with 301bs. effected. Compared with the several other me- 
thods of raising water, the daily produce of which is given in the table, p. 27 i of our 
first volume, we find it about equal to, if not a little superior, to the sucking- 
pump, which gives from about 800 to 810 rnaunds, raised It) feet, for the daily 
work of a man. An accurate comparison cannot be made, as the dailq work per- 
formed with the present pump is not mentioned. As it is so much cheaper and 
less liable to go out of repair than the sucking pump, there can be no question as 
to the value of the invention, although we fully expect that if our suggestion of 
the walking beam be adopted, the same quantity may he raised with one-third or 
one -fourth of the exertion at present used. 
r Ihe form of the present instrument has an advantage over that described by 
Professor Robison, inasmuch as it is applicable to shallow pieces of water, anil 
will yet raise the water to a considerable height. In the latter, the depth of the 
water must be equal to the height to which it is required to raise it. 
IX . — On the Rent and Produce of Land. 
To the Editor of Gleanings in Science. 
Sir, 
When I last addressed you, I had got upon a part of the subject under dis- 
cussion, which I thought was prudent to avoid ; I shall, therefore, retrace my steps, 
1 See Vol. I. p, 268. 
