Section 75

No. 75. A Steam-Boiler from which either a hot Blast may be driven into the fire, a Blackbird made to sing, or a Triton to blow a horn.

ANOTHER construction of the same kind is employed to produce the sound of a trumpet and the note of a blackbird. A boiler is made (fig. 75), of the same kind as the last, of which all the tubes in the base are bored through at each end, and near the surface there is a tube Q E, into which another tube K L is closely fitted, extending into the chamber for warm air, and moveable about tile pin K L. This tube is perforated by three holes, M, N, X, and similarly three holes are bored in Q E Opposite the holes M, N, X. Near x,an aperture is made in a support which receives a tube fitting closely into X and surmounted by the figure, as was described in the last paragraph: and from M and N two tubes extend, M 0, N P, bent at their upper extremities; these tubes pierce through the surface of the boiler, into which they are carefully soldered. Through the apertures other tubes pass, fitting tightly into the tubes P and 0. On one of these tubes is placed the figure of a sparrow, hollow within so as to receive water: the tube on which the bird sits is bent, and provided with a tuning-pipe, such as are made to produce notes, and the curved part of it passes as far as the water contained in the sparrow, so that, when the sound of the pipe reaches the water, the note of a blackbird is produced. In like manner the tube N P has another tube fitting closely into it, on which is placed a figure shaped like a triton with a trumpet in its mouth: the tube on which the triton is placed is moreover furnished with the mouthpiece and bell as usual, and when the vapour reaches these and enters them it will give out the sound of a trumpet. We must discover by trial when the holes in K L are opposite the tubes M 0 and N P, and when to X on which the figure is placed. Having learnt this, we must make corresponding marks on the pin K L, that the trumpet may sound, or the figure blow, or the blackbird's note be produced, at our pleasure. The arrangements about the cup and the ascent of the warm water are to be made according to the previous description.

Section 76.