puddled earth are made to receive the contributions of each bucket. The average lift of the Swape is seven feet, and by a series of these, one above the other, the water is finally delivered on the summit of the bank, thence to irrigate the vast plains beyond. The chain of pots is also seen side by side with the Swape, and is the more efficient mechanism, by delivering the water at once at the summit. It is, moreover, worked by animal power and but that it is taxed by the government double the sum paid by the Swape, would probably supersede it. The tympanum, the noria or Egyptain wheel, the Persian wheel, the chain of pots, and the screw, all improved devices to raise water, were of very ancient use and so remained until the introduction of the pump.

The chain-pump, which is in fact only a modification of the chain of pots, by passing the chain through a tight tube, round or square, and for pots substituting wooden or metallic pallets or pistons, fitting the interior of the tube and pushing the water before

them, was known in China from the earliest ages, but does not appear to have been introduced into Europe till about the middle of the seventeenth century they are chiefly ;

used now in an improved form on board ships of war.

The ordinary pump, or sucking-pump, as it ^vas at first called, though evidently known to the Greeks and Romans, and used in their ships, does not seem to have been much employed by them for domestic purposes. It was not till the fifteenth and sixteenth century that pumps became common and superseded the more ancient devices for raising water and even then the principle upon which the water was raised was little conceived of.