Excerpt from Popular Lectures on Scientific Subjects IN 1891 the seventieth birthday of Hermann von Helm holtz, and the forty-ninth anniversary of his taking the degree of Doctor of Medicine, was celebrated in Berlin in a manner which, whether for its universality or import ance, has, perhaps, never fallen to the lot of a Man of Science during his lifetime. The demand for a new edition of the translation of the two volumes of Von Helmholtz's Popular Scientific Lectures suggests that this is an appropriate occasion for a re-issue under conditions which make them accessible to a larger circle of readers. The present edition is identical with the preceding ones; discussing as they do, with the hand of a master, fundamental scientific problems, these Lectures are not likely to be soon out of date. To the second volume has been added a remarkable autobiographical account of the Author's scientific career and development, which formed the subject of an address given by Von Helmholtz in reply to the addresses of congratulation on the occasion of his Jubilee, This is taken, by kind permission of the publisher, M. Hirschwald, from a collection of the addresses and speeches delivered on that occasion. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.