Fig. 79.
The fusee windlass is shown in Fig. 79. This is an early invention designed to overcome in a mechanical method the greater weight which the rope hung at its extremity has, as compared to what it is when nearly wound up. At the bottom of the well the rope then being at its heaviest period is wound upon the small end of the fusee; and as the length diminishes it coils round the larger part. [(See Fig. 79)], which is however inaccurately drawn—as the bucket is at the top of the well; it should have been represented as suspended from the large end of the fusee.
The value of a device like this will be appreciated when the great depth of some wells is considered and the consequent additional weight of the chains. In the fortress of Dresden is a well eighteen hundred feet deep; at Augustburgh is a well in which half an hour is required to raise the bucket; and at Nuremburgh another, sixteen hundred feet deep. In all these, the water is raised by chains, and the weight of the one used in the latter is stated to be upwards of a ton.
Fig. 80.
The tympanum and noria in all their modifications have been considered as originating in the gutter or jantu, and the swape; while the machine we are now to examine is evidently derived from the primitive cord and bucket. The first improvement of the latter was the introduction of a pulley or sheave over which the cord was directed—the next was the addition of another vessel, so as to have one at each end of the rope, and the last and most important consisted in uniting the ends of the rope, and securing to it a number of vessels at equal distances through the whole of its length—and the chain of pots was the result. [(See Fig. 80.)]
The general construction of this machine will appear from an examination of those which are employed to raise water from Joseph’s well at Cairo, represented on [page 45]. Above the mouth of each shaft a vertical wheel is placed, over which two endless ropes pass and are suspended from it. These are kept parallel to, and at a short distance from each other, by rungs secured to them at regular intervals, so that when thus united, they form an endless ladder of ropes. The rungs are sometimes of wood, but more frequently of cord like the shrouds of a ship, and the whole is of such a length that the lowest part hangs two or three feet below the surface of the water that is to be raised. Between the rungs, earthenware vases (of the design shown at A A) are secured by cords round the neck, and also round a knob formed on the bottom for that purpose.
WHEEL AND AXLE.
Fig. 81.