of the coagulation of the blood; theory of the circulation of the blood; explanation of the flow of sap in plants; endosmosis of gases through thin films; measure of the force of endosmosis; respiration of fishes; action of organic muscle-fibre of the lungs; allotropism of living systems; new facts respecting the action of the skin; functions of nerve-vesicles and their electrical analogues; function of the sympathetic nerve; explanation of the action of certain parts of the auditory apparatus, particularly the cochlea and semicircular canals; new facts respecting the theory of vision and theory of muscular contraction. The special object of the book was, to apply physical theories in the explanation of physiological facts, to the exclusion of the so-called vital principle of the old physicians.
Dr. Draper is a man of a philosophical cast of mind, by which he was drawn to the study of phenomena in their more comprehensive aspects and relations. The wide range of his scientific acquirements, and especially his mastery of physiology, formed an admirable preparation for studying the subjects of human development and the course of civilization from a scientific point of view. His "Physiology" was accordingly soon followed by a work of which the intention was to show that societies of men advance under the government of law. This was entitled "A History of the Intellectual Development of Europe." Few philosophical works have attained so quickly to celebrity. Many editions of it have been published in this country, and it has been translated into almost every European language. The Westminster Review, speaking of it says: "It is one of the not least remarkable achievements in the progress of positive philosophy that have yet been made in the English tongue. A noble and even magnificent attempt to frame an induction from all the recorded phenomena of European, Asiatic, and North African history."
Though in his earlier years Dr. Draper was a skillful mathematical analyst, he has published but few mathematical papers, the most important being an investigation of the electrical conducting power of wires. This was undertaken at the request of Prof. Morse, at the time he was inventing his telegraph. The use made by Morse of this investigation is related by him in Silliman's American Journal of Science and Arts, December, 1843. The paper shows that an electrical current may be transmitted through a wire, no matter what the length may be, and that, generally, the conducting effect of wires may be represented by a logarithmic curve. Among electrical memoirs there is one on the tidal motions exhibited by liquid conductors, and one on the electro-motive power of heat, explaining the construction of some new and improved forms of thermo-electric batteries. An abstract of these improvements is given in the last edition of the "Encyclopædia Britannica" (Art. Voltaic Electricity).
Dr. Draper was the first person to obtain photographs of the diffraction spectrum given by a grating, and to show the singular advan-
