William Thomson, his "Account of Carnot's Theory," in which that great physicist first points out to the world the treasure so long concealed, unnoticed, among the scientific literature, already mainly antiquated, of the first quarter of the nineteenth century. The distinguished writer of this paper has kindly interested himself in the scheme of the Editor, and has consented to its insertion as a natural and desirable commentary upon the older work, and especially as exhibiting the relations of the fundamental principles discovered and enunciated by Carnot to the modern view of the nature of thermodynamic phenomena—relations evidently understood by that writer, but not by the leaders of scientific thought of his time, and therefore ignored by him in the construction of his new science.
The Appendix contains a number of Carnot's own notes, too long to be inserted in the body of the paper in its present form, and which have therefore been removed to their present location simply as a matter of convenience in book-making.
The dedication of the work to the grand-nephew of the author, who by a singular coincidence happens to-day to occupy the highest position that any citizen can aspire to reach in that
