The square openings represented on each side of the upper shaft are sections of the spiral passage, and the zig-zag lines indicate its direction. The wheels at the top carry endless ropes, the lower parts of which reach down into the water; to these, earthenware vases are secured by ligatures (see A A) at equal distances through the whole of their length, so that when the machinery moves these vessels ascend full of water on one side of the wheels, discharge it into troughs as they pass over them and descend in an inverted position on the other side. [Illustration: CHINESE WINDLASS.] This celebrated production of former times, as will be perceived, resembles an enormous hollow screw, the center of which forms the well and the threads a winding stair-case around it. To erect of granite, a flight of “geometrical” or “well stairs,” two or three hundred feet high, on the surface of the ground, would require extraordinary skill, although in its execution every aid from rules, 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 _downwards_ by excavation alone, in the dark bowels of the earth, is a more arduous undertaking, especially as deviations from the correct lines could not be remedied; yet in Joseph’s well, the partition of rock between the pit and the passage-way, and the uniform inclination of the latter, seem to have been ascertained with equal precision, as if the whole had been constructed of cut stone on the surface. Was the pit, or the passage, formed first; or were they simultaneously carried on, and the excavated masses from both borne up the passage, are unanswered questions. [Illustration: ANGLO-SAXON CRANE.] The extreme thinness of the partition wall, excited the astonishment of M. Jomard, whose account of the well is inserted in the second volume of Memoirs in Napoleon’s great work on Egypt. It is, according to him, but sixteen centimetres thick, [about six inches!] He justly remarks that it must have required singular care to leave and preserve so small a portion while excavating the rock from both sides of it. It would seem no stronger in proportion, than sheets of paste-board placed on edge, to support one end of the stairs of a modern built house, for it should be borne in mind, that the massive roof of the spiral passage _next the well_, has nothing but this film of rock to support it, or to prevent from falling, such portions as are loosened by fissures, or such, as from changes in the direction of the strata, are not firmly united to the general mass. But this is not all: thin and insufficient as it may seem, the bold designer has pierced it through its whole extent with semi-circular openings, to admit light from the well: those on one side are shown in the engraving. [Illustration: SWAPE OR SWEEP, A. D. 1493.]