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Chap. 9]
high above the mouth of the well, and then driving fhe animal in a directline from it, and to a distance equal to its depth, when the bücket chargedwith the liquid would be raised from the bottom. This, the most directand efficient, was, (it is believed,) the identical mode adopted, and likeother devices of the ancients, it is still continued by their descendants inAfrica and Asia . Its value in the estimation of the moderns, may belearned from the fact, that it is adopted in this and other cities for raisin gcoals, &c. from the holds of ships ; for which and similar purposes, it hasbeen in use for ages in Europe. It has also been used to work pumps,the further end of the rope being attached to a heavy piston working ina very long chamber or cylinder.
This was probably one of the first operations, and certamly one of themost obvious, where human labor was superseded by that of animals, andin accomplishing it, the pulley itself was perhaps discovered. This modeis common in Egypt, Arabia, India —through all Hindostan, and variousother parts of the east. Mr. Elphinstone mentions a large well under thewalls of the fort at Bikaneer, from fifteen to twenty-two feet in diameter,and three hundred feet deep. In this well four large buckets are used,each thus drawn up by a pair of oxen, and all worked at the same time.When any one of them was let down, “its striking the water, made anoise like a great gun.” But simple as this mode of raising water by animalsis, it is capable of an improvement equally simple, though not perhaps ob-vious to general readers. It was not however left to modern mechanicians todiscover, but is one among hundreds of ancient devices, whose origin islost in the remoteness of time. It is this—Instead of the animal recedingfrom the well on level ground, it is made to descend an inclined plane, sothat the weight of its body contributes towards raising the load. This ischaracteristic of Asiatic devices. At a very early period, the principleof combining the tveight of men and animals with their muscular energy,m propelling machines, was adopted. We shall meet with other exam-ples of it.
PULLEY AND TWO BUCKETS.
The addition of another bücket, so as to have one at each end of therope, was the next Step in the progress of improvement; and although sosimple a device may appear too obvious to have remained long unper-ceived, and one which required no Stretch of intellect to accomplish, itwas one of no small importance, since it effected what is seldom witnessedm practical mechanics—a saving both of time and labor. Thus, by it,the empty vessel descended and became filled, as the other was elevated,.