THE CORRELATION AND CONSERVATION OF FORCES: A Series of Expositions, BY PROF. GROVE, PROF. HELMHOLTZ, DR. MAYER, WITH AN INTRODUCTION AND BRIEF BIOGRAPHICAL NOTICES OF THE BY EDWARD L. YOUMANS, M. D. -The highest law in physical science which our faculties permit us to perceive-the NEW YORK: D. APPLETON AND COMPANY, 443 & 445 BROADWAY. 1865. 5mm THE NEWYORK 232288 ASTOR LENOX AND TILDEN FOUNDATIONS 1901 ENTERED, according to Act of Congress, in the year 1864, by D. APPLETON AND COMPANY, In the Clerk's Office, of the District Court of the United States for the Southern District of New York. It seems peculiarly appropriate that this volume should be dedicated to you. Knowing the eminent esteem in which you are held in the circles of European science, I cannot doubt that the distinguished authors of the following essays would cordially approve this connection of your name with their introduction to the American public. There is, besides, a further reason for this in that large coincidence of purpose which is manifest in their labors and your own. For while the pervading design of the present collection is to widen the range of thought by unfolding a broader philosophy of the energies of nature, your own comprehensive course of research-beginning with an extended series of experimental investigations in chemical physics and physiology, and rising to the consideration of that splendid problem, the bearing of science upon the History of the Intellectual Development of Europe-has powerfully contributed to the same noble end; that of elevating the aim and enlarging the scope of scientific inquiry. I gladly avail myself of this occasion to say how greatly I am indebted to your writings, in which accurate and profound instruction is so often and happily blended with the charms of poetic eloquence. That you may live long to enjoy your well-won honors, and to contribute still further to the triumphant advance of scientific truth, is the heartfelt wish of Yours truly, E. L. Y. PREFACE. In his address before the British Association for the Advancement of Science last year, the President remarked that the new views of the Correlation and Conservation of Forces constitute the most important discovery of the present century. The remark is probably just, prolific as has been this period in grand scientific results. No one can glance through the current scientific publications without perceiving that these views are attracting the profound attention of the most thoughtful minds. The lively controversy that has been carried on for the last two or three years respecting the share that different men of different countries have had in their establishment, still further attests the estimate placed upon them in the scientific world. But little, however, has been published in this country upon the subject; no complete work, I believe, except the admirable volume of Prof. Tyndall on "Heat as a Mode of Motion," in which the new philosophy is adopted, and applied to the explanation of thermal phenomena in a very clear and forcible manner. I have, therefore, thought it would be a useful service to the public to reissue some of the ablest presentations of these views which have appeared in Europe, in a compact and convenient form. The selection of these discussions has been determined by a desire to combine clearness of exposition with authority of statement. In the first of these respects the essays will speak for themselves; in regard to the last I may remark that all the authors quoted stand high as founders of the new theory of forces. Although I am not |