The Principles of Mechanics presented in a New Form

GREAT expectations were aroused by the publication, in 1894, of a book by Heinrich Hertz, with the title, “Die Principien der Mechanik in neuem Zusam-menhange dargestellt.” Perhaps it would set out the received theory of dynamics in strictly logical sequence; perhaps it would present a complete theory of energy independent of the notion of force; perhaps it would bridge the gap between the molecular and mechanical standpoints. Whether it would do any of these things or not, what Hertz might have to say would certainly be worthy of attention. Hertz died before the work was printed, and the task of seeing it through the Press was entrusted to Dr. P. Lenard. He tells us that the author had devoted the last three years of his life to the book, the last two being spent in perfecting its form; and, although there are indications that he was not even then completely satisfied, the work may fairly be regarded as the mature expression of his deliberate thought on the subject.The Principles of Mechanics presented in a New Form.By Heinrich Hertz. Authorised English translation, by D. E. Jones and J. T. Walley. Pp. xxviii + 276, (London: Macmillan and Co., Ltd., 1899.)