Page:Report from the Select Committee on Steam Carriages.pdf/94



John Farey, Esq. 10 August, 1831. high pressure engines, many years ago, in order to mix with the smoke ascending in the chimney, and thus get rid of the waste steam; it improved the draft in that way, by rendering the smoke more buoyant, but only in a slight degree; but the waste steam was not discharged through a contracted orifice to give it velocity, nor was it directed upwards as is now done by Mr. Stephenson; and that vertical jet of steam in the centre of the chimney, gives such an intensity of draft through the fire as was never procured before, and with the further advantage that the rapidity of draft so produced, increases whenever the engines work faster, and discharge more steam, just in proportion as the demand for fire and steam increases by that working faster.

Is there any noise occasioned in that way?—Yes; but the sound is directed upwards by the chimney, and is not much heard in the locomotive Engines on the railway when they are in the open air, but when they pass under the bridges, the sound is reverberated down again by the arch, and then it sounds very loud. The noise is no great consequence there, and no particular pains have been taken to avoid it. The metal pipe of the chimney has something of the effect of an organ-pipe or trumpet, but it is probable the sound might be deadened.

Will the burning out of the plates of Mr. Hancock's boiler, that you spoke of, be attended with risk of explosion of the whole boiler, or only of the smaller divisions of the boiler?—It will be attended with no violence which could be called an explosion, nor with any danger whatever, but only with the inconvenience of disabling the Carriage until the ruptured chamber is replaced by another. The rupture or crack of the metal plate at the burned place, would let out the water and steam very gradually into the fire, and probably extinguish it. All steam boilers burn out in that manner sooner or later. The different chambers of Mr. Hancock's boiler are kept together by six very strong bolts, which pass through them all, and which are quite protected from the action of the fire; to burst the boiler those bolts must give way altogether,