producing steam. The form of every part of the boiler being cylindrical, is that which, mechanically considered, is most favourable to strength. I cannot conceive the possibility that a boiler of this kind, properly constructed, and previously proved in the usual way, could, under any supposable circumstances, explode.
When the steam passes from the cylinder above the fire-door to the separator, it is charged with water suspended in it in minute subdivision, an effect called by engineers priming. If the water thus mechanically combined with the steam, were allowed to pass through the engines, several injurious effects would be produced, among which may be mentioned the waste of all the heat which that water would carry with it. This is a defect common, in various degrees, to all the locomotive engines, except the one now under consideration. The purpose of the separator is to disengage or separate the water from the steam in which it is mechanically suspended; and this is accomplished merely by allowing it to descend by its gravity to the bottom of the separator. It collects there, and is thence conducted back to the boiler to be circulated again.
The next contrivance which claims notice in this machine is the method of blowing the fire. I have already explained the means adopted in the railway engines for accomplishing this, by throwing the waste steam from the cylinders into the chimney. This, however, is attended with a puffing noise, arising from the sudden blasts of steam ejected by the alternate strokes of the piston, and which is increased by the form of the chimney, and the aperture by which they escape. Such a noise would be inconvenient and objectionable. Yet to put aside the use of the waste
