IT may perhaps have occurred to others besides myself that the term “degradation”—as applied to the transmutation, for instance, of mechanical energy into heat energy—is a rather stronger one than our present knowledge warrants us in using: that it casts, in fact, an unmerited slur on the character of that eminently respectable concept energy. We seem hardly justified in supposing that any intrinsic deterioration of the energy takes place in such transmutations as the above.