Produced by Anna Hall, Albert László and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) POPULAR SCIENTIFIC LECTURES. BY THE SAME AUTHOR. THE SCIENCE OF MECHANICS. Translated from the Second German Edition by T. J. McCormack. 250 Cuts and Illustrations. 534 Pages. Half Morocco, Gilt Top. Price, $2.50. CONTRIBUTIONS TO THE ANALYSIS OF THE SENSATIONS. Translated by C. M. Williams. With Notes and New Additions by the Author. 200 Pages. 36 Cuts. Price, $1.00. POPULAR SCIENTIFIC LECTURES. Translated by T. J. McCormack. Third Revised and Enlarged Edition. 411 Pages. 59 Cuts. Cloth, $1.50; Paper, 50 cents. THE OPEN COURT PUBLISHING CO., 324 DEARBORN ST., CHICAGO. POPULAR SCIENTIFIC LECTURES BY ERNST MACH FORMERLY PROFESSOR OF PHYSICS IN THE UNIVERSITY OF PRAGUE, NOW PROFESSOR OF THE HISTORY AND THEORY OF INDUCTIVE SCIENCE IN THE UNIVERSITY OF VIENNA TRANSLATED BY THOMAS J. McCORMACK THIRD EDITION, REVISED AND ENLARGED WITH FIFTY-NINE CUTS AND DIAGRAMS CHICAGO THE OPEN COURT PUBLISHING COMPANY FOR SALE BY KEGAN PAUL, TRENCH, TRUEBNER & CO., LONDON 1898 COPYRIGHT BY THE OPEN COURT PUBLISHING CO. Pages 1-258 } } in 1894. Pages 338-374 } Pages 259-281 in 1896. Pages 282-308 in 1897. Pages 309-337 in 1898. AUTHOR'S PREFACE TO THE FIRST EDITION. Popular lectures, owing to the knowledge they presuppose, and the time they occupy, can afford only a _modicum_ of instruction. They must select for this purpose easy subjects, and restrict themselves to the exposition of the simplest and the most essential points. Nevertheless, by an appropriate choice of the matter, the _charm_ and the _poetry_ of research can be conveyed by them. It is only necessary to set forth the attractive and the alluring features of a problem, and to show what broad domains of fact can be illuminated by the light radiating from the solution of a single and ofttimes unobtrusive point. Furthermore, such lectures can exercise a favorable influence by showing the substantial sameness of scientific and every-day thought. The public, in this way, loses its shyness towards scientific questions, and acquires an interest in scientific work which is a great help to the inquirer. The latter, in his turn, is brought to understand that his work is a small part only of the universal process of life, and that the results of his labors must redound to the benefit not only of himself and a few of his associates, but to that of the collective whole. I sincerely hope that these lectures, in the present excellent translation, will be productive of good in the direction indicated. E. MACH. PRAGUE, December, 1894. TRANSLATOR'S NOTE TO THE THIRD EDITION.