This distinguished American sxivant, who has just accepted a chair in the University of Glasgow, Scotland, in writing of the physical power which England derives from the transformation of the latent power of coal into active force, states the following interesting facts.:— " Each acre of a coal seam, four feet in thickness, and yielding one yard net of pure fuel, is equivalent to about 5,000 tuns ; and possesses, therefore, a reserve of mechanical strength in its fuel equal to the life-labor of more than 1,600 men. Each square mile of one such single coal bed contains 8,000,000 tuns of fuel; equivalent to 1,000,000 of men laboring through twenty years of their ripe strength. Assuming, for calculation, that 10,000,000 tuns out of the present annual products of the British coal mines, (namely, 65,000,000,) are applied to the production of mechanical power, then England annually summons to her aid an army of 3,300,000 fresh men pledged to exert their fullest strength through twenty years. Her actual annual expenditure of power then is represented by 6G,000,000 of able-bodied laborers. The latent strength resident in the whole coal product of the kingdom may, by the same process, be calculated at more than 400,000,000 of strong men, or more than double the number of the adult males now upon the globe."