Note 33 — Chapter XI · LOCOMOTIVE ENGINES ON TURNPIKE ROADS.

Connected with this blowing box, is another ingenious apparatus of considerable practical importance. The pipe through which the water which feeds the boiler is conducted to it from the tank is carried through this blowing box, within which it is coiled in a spiral form, so that an extensive thread of the feeding water is exposed to the heat of the waste steam which has escaped from the cylinders, and which is enclosed in this blowing box. In passing through this pipe the feeding water is raised from the ordinary temperature of about 60° to the temperature of 212°. The fuel necessary to accomplish this is, therefore, saved, and the amount of this is calculated at 1/6th of all that is necessary to evaporate the water. Thus, 1/6th of the expense of fuel is saved. But, what is much more important in a locomotive engine, a portion of the weight of the engine is saved without any sacrifice of its power. There is still another great advantage attending this process. The feeding water in the worm just mentioned, while it takes up the heat from the surrounding steam in the blowing box, condenses 1/6th of the waste steam, which is thence conducted to the tank, from which the feeding water is pumped, saving in this manner 1/6th in weight and room of the water necessary to be carried in the carriage for feeding the boiler.[33]