Excerpt from Popular Lectures on Scientific Subjects In compliance with many requests, I beg to offer to the public a series of popular Lectures which I have delivered on various occasions. They are designed for readers who, without being professionally occupied with the study of Natural Science, are yet interested in the scientific results of such studies. The difficulty, felt so strongly in printed scientific lectures, namely, that the reader cannot see the experiments, has in the present case been materially lessened by the numerous illustrations which the publishers have liberally furnished. The first and second Lectures have already appeared in print; the first in a university programme which, however, was not published. The second appeared in the 'Kieler Monatsschrift' for May, 1853, but owing to the restricted circulation of that journal, became but little known; both have, accordingly, been reprinted. The third and fourth Lectures have not previously appeared. These Lectures, called forth as they have been by incidental occasions, have not, of course, been composed in accordance with a rigidly uniform plan. Each of them has been kept perfectly independent of the others. 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.