THE INTERNATIONAL SCIENTIFIC SERIES. VOLUME VII. THE INTERNATIONAL SCIENTIFIC SERIES. _Works already Published._ I. FORMS OF WATER, IN CLOUDS, RAIN, RIVERS, ICE, AND GLACIERS. By Prof. JOHN TYNDALL, LL. D., F. R. S. 1 vol. Cloth. Price, $1.50. II. PHYSICS AND POLITICS; OR, THOUGHTS ON THE APPLICATION OF THE PRINCIPLES OF “NATURAL SELECTION” AND “INHERITANCE” TO POLITICAL SOCIETY. By WALTER BAGEHOT, Esq., author of “The English Constitution.” 1 vol. Cloth. Price, $1.50. III. FOODS. By EDWARD SMITH, M. D., LL. B., F. R. S. 1 vol. Cloth. Price, $1.75. IV. MIND AND BODY: THE THEORIES OF THEIR RELATIONS. By ALEX. BAIN, LL. D., Professor of Logic in the University of Aberdeen, 1 vol., 12mo. Cloth. Price, $1.50. V. THE STUDY OF SOCIOLOGY. By HERBERT SPENCER. Price, $1.50. VI. THE NEW CHEMISTRY. By Prof. JOSIAH P. COOKE, Jr., of Harvard University. 1 vol., 12mo. Cloth. Price, $2.00. VII. THE CONSERVATION OF ENERGY. By Prof. BALFOUR STEWART, LL. D., F. R. S. 1 vol., 12mo. Cloth. Price, $1.50. VIII. ANIMAL LOCOMOTION; OR, WALKING, SWIMMING, AND FLYING, WITH A DISSERTATION ON AËRONAUTICS. By J. BELL PETTIGREW, M. D., F. R. S. E., F. R. C. P. E. 1 vol., 12mo. Fully illustrated. Price, $1.75. IX. RESPONSIBILITY IN MENTAL DISEASE. By HENRY MAUDSLEY, M. D. 1 vol., 12mo. Cloth. Price, $1.50. X. THE SCIENCE OF LAW. By Prof. SHELDON AMOS. 1 vol., 12mo. Cloth. Price, $1.75. XI. ANIMAL MECHANISM. A TREATISE ON TERRESTRIAL AND AËRIAL LOCOMOTION. By E. J. MAREY. With 117 Illustrations. Price, $1.75. XII. THE HISTORY OF THE CONFLICT BETWEEN RELIGION AND SCIENCE. By JOHN WM. DRAPER, M. D., LL. D., author of “The Intellectual Development of Europe.” Price, $1.75. XIII. THE DOCTRINE OF DESCENT, AND DARWINISM. By Prof. OSCAR SCHMIDT, Strasburg University. Price, $1.50. XIV. THE CHEMISTRY OF LIGHT AND PHOTOGRAPHY. IN ITS APPLICATION TO ART, SCIENCE, AND INDUSTRY. By Dr. HERMANN VOGEL. 100 Illustrations. Price, $2.00. XV. FUNGI; THEIR NATURE, INFLUENCE, AND USES. By M. C. COOKE, M. A., LL. D. Edited by Rev. M. J. BERKELEY, M. A., F. L. S. With 109 Illustrations. Price, $1.50. XVI. THE LIFE AND GROWTH OF LANGUAGE. By Prof. W. D. WHITNEY, of Yale College. Price, $1.50. XVII. THE NATURE OF LIGHT, WITH A GENERAL ACCOUNT OF PHYSICAL OPTICS. By Dr. EUGENE LOMMEL, Professor of Physics in the University of Erlangen. With 188 Illustrations and a Plate of Spectra in Chromo-lithography. (_In press._) THE INTERNATIONAL SCIENTIFIC SERIES. THE CONSERVATION OF ENERGY. BY BALFOUR STEWART, LL. D., F.R.S., PROFESSOR OF NATURAL PHILOSOPHY AT THE OWENS COLLEGE, MANCHESTER. _WITH AN APPENDIX_, TREATING OF THE VITAL AND MENTAL APPLICATIONS OF THE DOCTRINE NEW YORK: D. APPLETON AND COMPANY, 549 & 551 BROADWAY. 1875. ENTERED, according to Act of Congress, in the year 1874, by D. APPLETON & COMPANY, In the Office of the Librarian of Congress, at Washington.