asses or mules. It is six feet four in-ches wide, and seven feet two incheshigh. Between it and the interior ofthe well, a wall of rock is left, to pre-vent persons falling into, or even look-ing down it, (which in some cases wouldbe equally fatal,) except through certainopenings or Windows, by means of which,it is faintly liglited from the interior ofthe well: by this passage the animalsdescend, which drive the machinery thatraises the water l'rom the lower shaftinto the reservoir or basin, from whichit is aga.in elevated by similar machinery,and other oxen on the surface of theground. See figure. In the lo wer shaft, apath is also cut down to the water, but asno partition is left between it and the well,it is extremely perilous for strangers todescend.

The square openings represented oneach side of the upper shaft, are sec-tions of the spiral passage, and the zig- *zag lines indicate its direction. Thewheels at the top carry endless ropes,the lower parts of which reach downto the water; to these, earthenware va-ses are secured by ligatures, see A, A,at equal distances through the wdhole oftheir length, so that when the machineryis moved, these vessels ascend full ofwater on one side of the wheels, dis-charge it into troughs as they pass overthem and descend in an inverted po-sition on the other. For a further de-scription of this apparatus, see the chap-ter on the chain of pots.

This celebrated production of formertimes, it will be perceived, resembles anenormous hollow screw, the centre ofwhich f'orms the well, and the threads, awinding stair-case round it. To erectof granite a flight of “ geometrical” or“ well stairs,” two or three hundred feethigh, on the surface of the ground,would require extraordinary skill; al-though in the execution, every aid fromrules, measures, and the light of day,would guide the workmen at every Step;but to begin such a work at the top,and construct it Aoivnwards by excava-tion alone, in the dark bowels of theearth, is a more arduous undertaking,especially as deviations from the correctlines could not be remedied ; yet in Jo-