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 are quite separate, as you may know—the showing would he much more favorable.

It will be instructive, I think, to trace out the causes of the great waste of power that I have just pointed out, and to see if there are no means of remedying them. And if you will follow me, they will be very apparent.

The first and greatest source of loss resides in the difficulty—I may, I think, safely say the impossibility—of burning solid fuel economically in any form of furnace that has yet been devised; and this prime difficulty is an unanswerable argument in favor of the substitution of liquid or gaseous fuel for steam-making as for other purposes. Let us analyze the matter: The buyer of coal purchases at the outset at least 10 to 15 per cent. of non-combustible and useless material with every pound of coal, in the form of ash; while at least 5 per cent. more of the coal is lost by falling through the grate-bars in the form of the dust or partially burned fragments that find their way into the ash-pit unutilized. If even now, with so much waste as I have just indicated, we could really turn to useful account the whole of the thermal effect of the 85 per cent, or 80 per cent, of the combustible that we have left, we might well be content; but such is far from being the case. The furnace gases can not, by any possible mode of constructing boilers, be retained long enough in contact with the steam-generator to yield up all their heat, and they are thrown out from the chimney frequently at a temperature of 800° Fahr.; and, what is still worse, their combustion is frequently so imperfect that they carry off with them out of the chimney great volumes of unburned carbon in the form of smoke; the cold air with which the fuel is fed, and which must become highly heated before it will begin to combine with the fuel, and which abstracts this heat from the glowing coals through which it passes, is another serious item of loss, which is intensified by the necessity of frequently opening the furnace-doors when large volumes of cold air rush into the fire-space; and, lastly, the conduction and radiation of heat from the generator to surrounding objects complete the category of losses. Summing up all the items of loss in the steam-generator, it is probable that with the best forms of boilers which it has been possible to construct, not more than 25 per cent. of the theoretical thermal effect of the fuel is utilized in the generation of steam; and of this 25 per cent., from 5 to 10 per cent, is lost somewhere on the passage of the steam from the boiler to and through the engine by condensation in steam-pipes, and friction of the machinery, leaving us but 15 or 20 per cent, actually realized in practice. I beg that you will not think that I have purposely made the case of the steam-engine worse than it is; for, so far from doing so, I have actually made out the most favorable possible showing for it, by selecting for my example the best practice of the best makers.

Much of this loss, possibly the half of it, I have no hesitation in