civil engineer, and has not even had the experience of running a small paper mill, might "guess" that such a stream would furnish, with a head of thirty feet, as much as an eight hundred horse power.

But it is not eight hundred horse power, nor four hundred that is required to operate the drilling machinery and ventilate the tunnel; for two hundred and eight horse power is all that has ever been used or needed at Mt. Cenis. This leaves a pretty wide margin for drouths, evaporation, and other contingencies.

In his observations upon the power required, Mr. Bird becomes severe and sarcastic. He assails the opinion of the commissioners that "the loss of power by carrying the compressed air through five miles of pipe will be quite insignificant," and after asserting that there are no data by which to test the correctness of this opinion, and claiming "some experience in such matters," prefers that such an "experiment". should be tried with somebody's money besides his own. It is gratifying to learn from Mr. Bird, himself, that he he has had experience in the matter of compressed air as a motive power, and that a "cussed furriner," as he elegantly phrases it is not to be allowed to bear off the palm of this great discovery uncontested. Doubtless M. Sommeiller will yield to the superior science and sagacity of Mr. Bird; but our countryman should lose no time in informing his fellow citizens of his investigations, experiments and success in arriving at the conclusion that compressed air cannot "be carried through five miles of pipe without a very serious loss of power through friction, leakage, &c." But, unfortunately for this view of the case, there are data establishing the fact that compressed air has been conveyed through more than two miles of pipe at Mt. Cenis, and then operated the drills without any appreciable loss of power. If there is no loss in two miles, how can there be in five? It is no longer an experiment, but an established scientific fact.

The size of the present excavation next engages the attention of our observer, and he calls the commissioners to account because they have not followed their own recommendation to excavate the Tunnel to its full dimensions as the work proceeds. Since their recommendation was made in the winter of 1863, the commissioners have had much experience, and the price of labor has doubled. Only a small number of men can work on a heading, but when a heading has been advanced a large number of workmen can follow rapidly in enlarging the excavation, and will soon overtake those engaged on the heading. At Mt. Cenis, the pneumatic drills are only used on the heading, and the enlargement is done by numerous laborers with hand drills. It is apparent that the commissioners have been actuated solely by motives of economy in prosecuting the heading alone, at the present high rates of labor. The work of enlargement is comparatively easy and rapid, and might well await a decline in the cost of labor, though it must be admitted that the importance of completing this noble work, ought to outweigh the consideration of any possible cost.