LS

AND SIMILAR MACHINES.

43

the supply at top, fixed in the pentrough, and another at bottom which regulates the expenditure; the pressure of the atmosphere on the top is supposed to render the whole column effective. The fixed wheel forms a bottom to the upper portion of the cylinder, which must be firmly secured to a foundation of masonry or timber. The upright shaft or axle is fitted into the moving wheel and turns with it, passing through a collar properly bored and lined with brass, in the centre of the upper or fixed wheel; it is steadied and secured by another collar formed on a frame or bracket, screwed to the top of the cylinder, which may be dispensed with if the nether millstone be used instead; but, in the sketch here given, the wheel is intended to turn other kinds of machinery.

It will be observed that, in the present instance, the upper portion of the cylinder, above the fixed wheel, is made of cast iron, and that the lower part is made of wrought-iron plates. The pressure of the water is directed by the vanes or guide-curves of the upper wheel into the buckets of the lower one, so as to bear upon them with the greatest effect, while, by the regulation of the two sluices (which are not shown in the woodcut), the cylinder is kept full, and the descending column of water passes like an eddy through the wheels, with a force proportioned to the whole height, for the lower end of the cylinder is immersed in the water, which in ordinary times just covers the outgoing opening, and in flood times rises above it, so that the power due to the difference between the surfaces of the dam and the tail water may always be available.

This combination is a great improvement upon the wheels at Toulouse, before described; and the same principles have been further developed by MM. Fromont, who obtained

the Council medal, at the Great Exhibition of 1851, for their Horizontal Water-Mill of fifty-five horses' power, constructed on the system of M. Fontaine Baron—a machine capable of the nicest adjustment, and applicable to any manufacture, however delicate, as the spinning of silk and fine yarns of any kind, and giving a useful effect of 75 per cent.

In several respects this resembles the last-described, inasmuch as there are two wheels placed in the same manner, either at the lower end of a large iron cylinder open at the top, or at the bottom of a cistern of strong woodwork. The reservoir or cistern intended to be used for this wheel was about 8 feet high, but it was not exhibited, as it would have prevented a complete view of the interior arrangements. It was therefore removed, and the upper work for regulating the sluices, together with the governor, were placed on a cast-iron frame above, supported by six pillars. The upper, or fixed wheel, had a strong flanch surrounding it and cast with it, having provision made for securing it with screw-bolts to the bottom of the cistern or tank, and beneath the revolving, or under wheel (in this case not included in a cylinder, as in Koechlin's plan); a clear way of escape for the effluent water, after it had done its duty, was left on all sides. The fixed wheel, thus attached by its flanch to the bottom of the tank, was about 6 feet in diameter, and had a strong cast-iron pipe, about a foot in diameter, fixed by bolts to its centre, and rising up above the level of the cylinder or cistern, where it was secured by a strong frame, serving to bind together the whole fabric and to support the axis of the revolving wheel which passed through the pipe and worked in a gun-metal collar above.

In the fixed wheel there were forty-two openings disposed in two concentric circles; the outer circle having twentyfour, and the inner circle eighteen; these openings radiated from the centre of the wheel, and were formed so as to direct the water into the buckets of the revolving wheel below it. The outside diameter of the outer circle of openings was about 6 feet, and the inside diameter of the inner circle about 3 feet; there was a division, or partition of an inch in thickness, between the two circular series of openings, so that they might be about 8 inches long.

Each of these openings was fitted with a sluice made of cast iron, with the back of it properly curved in a vertical direction, so as to direct the water in passing through the openings and lead it fairly into the buckets.