Chinese Windlass.

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Chap. 10.]

it has probably been in uninterrupted use since the Roman era. a Some-times it was placed on one side of the well, and at a short distance fromit, the ropes passing through pulleys that were suspended over its mouth.By this arrangement water may be raised to any required height abovethe windlass; an advantage in some cases very desirable. Belidor hasgiven a similar figure, and observes that such machines were extensivelyused in the Low Countries. b Soraetimes a series of pulleys were com-bined with it. In an old work, we have seen the windlass attached to alarge tub in which water or coal was raised, so that one or more personsmight ascend and descend, without the aid of others on the surface of theground; the ropes being passed through a block above the mouth of thepit. c It is very probable that these applications of it were known to theGreeks and Romans. Switzer, in his ‘ Ilydrostatics,’ says, the ancientsused the windlass for raising water, and that all their machines of a similarconstruction wrnre classed under the general name of Budromia.

There is a very peculiar and exceedingly ingenious modification ofthe windlass, which may here be noticed, and for which we are indebtedto the Chinese . It furnishes the means of increasing mechanical energyto almost any extent, and as it is used by them to raise water from someof those prodigiously deep wells already noticed, (p. 30,) a figure of it,(No. 19.) is inserted. The roller consists of two parts of unequal di-ameters, to the extremicies of which, the ends of the rope are fastened onopposite sides, so as to wind round both parts in different directions. Asthe load to be raised is suspended to a pulley, (See fig.) every turn of theroller r^jses a portion of the rope equal to the circumference of the thickerpart, but at the same time lets down a portion equal to thatof the small er;consequently the weight is raised at each turn, through a space equal onlyto half the difference between the circumferences of the two parts of theroller. The action of this machine is therefore slow, but the mechanicaladvantages are proportionably great. d

No. 19. Chinese Windlass. No. 20. Fusee Windlass.

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This is the neatest and most simple modification of the wheel and axle,that human ingenuity has devised, and is a proof that the principles ofmechanical Science were well understood in remote ages; for every me-

a De Re Metallica, Basil. 1657. p. 118, 119, 160.b Architecture^ Hydrauliqne, tom. 2, p. 333.

'Besson’s Theatre des Instrvmens Mathematiques et Mechaniques. A Lyon, 1579.‘The Chinese, ’ by J. F- Davis, vol. ii, 286.