THE SCIENCE OF MECHANICS- A CRITICAL AND HISTORICAL ACCOUNT OF ITS DEVELOPMENT by DR. ERNST MACH Originally published in 1919. TRANSLATORS PREFACE TO THE SECOND ENGLISH EDITION: SINCE the appearance of the first edition of the present translation of Machs Mechanics , the views which Professor Mach has advanced on the philoso phy of science have found wide and steadily increas ing acceptance. Many fruitful and elucidative con troversies have sprung from his discussions of the historical, logical, and psychological foundations of physical science, and in consideration of the great ideal success which his works have latterly met with in Continental Europe, the time seems ripe for a still wider dissemination of his views in English-speaking countries. The study of the history and theory of science is finding fuller and fuller recognition In our universities, and it Is to be hoped that the present ex emplary treatment of the simplest and most typical branch of physics will stimulate further progress in this direction, The text of the present edition, which contains the extensive additions made by the author to the Die Mechanik in ihrer Entwickelung historisch-kritisch dargesiellt. Von Dr. Ernst Mach, Professor an der Universitat zu Wien. Mit 257 Abbildungen. First German edition, 1883. Fourth German edition, 1901. First edition of the English translation, Chicago, The Open Court Publishing Co., 1893 latest German editions, has been thoroughly revised by the translator. All errors, either of substance or typography, so far as they have come to the trans lators notice, have been removed, and in many cases the phraseology has been altered. The sub-title of the work has, in compliance with certain criticisms, also been changed, to accord more with the wording of the original title and to bring out the idea that the work treats of the principles of mechanics predomi nantly under the aspect of their development Entwicke lung. To avoid confusion in the matter of references, the main title stands as in the first edition. The authors additions, which are considerable, have been relegated to the Appendix. This course has been deemed preferable to that of incorporating them in the text, first, because the numerous refer ences in other works to the pages of the first edition thus hold good for the present edition also, and sec ondly, because with few exceptions the additions are either supplementary in character, or in answer to criticisms. A list of the subjects treated in these ad ditions is given in the Table of Contents, under the heading Appendix on page xix. Special reference, however, must be made to the additions referring to Hertzs Mechanics pp. 548-555, and to the history of the development of Professor Machs own philosophical and scientific views, notably to his criticisms of the concepts of mass, inertia, ab solute motion, etc., on pp. 542-547, 555574, and 579 - 583. The remarks here made will be found highly elucidative, while the references given to the rich literature dealing with the history and philosophy of science will also be found helpful. As for the rest, the text of the present edition of the translation is the same as that of the first. It has had the sanction of the author and the advantage of revision by Mr. C. S. Peirce, well known for his studies both of analytical mechanics and of the his tory and logic of physics. Mr. Peirce read the proofs of the first edition and rewrote Sec. 8 in the chapter on Units and Measures, where the original was in applicable to the system commonly taught in this county. THOMAS J. McCoRMACK. LA SALLE, ILL., February, 1902.