Transcriber Note Text emphasis denoted by _Italics_. [Illustration: JOHN TYNDALL] THE FORMS OF WATER IN CLOUDS AND RIVERS ICE AND GLACIERS BY JOHN TYNDALL, LL.D., F. R. S. _WITH TWENTY-FIVE ILLUSTRATIONS DRAWN AND ENGRAVED UNDER THE DIRECTION OF THE AUTHOR_ NEW YORK D. APPLETON AND COMPANY 1899 Copyright, 1872, By D. APPLETON AND COMPANY. Electrotyped and Printed at the Appleton Press, U. S. A. AMERICAN PREFACE TO THE INTERNATIONAL SCIENTIFIC SERIES. The rapid development of science in the present age, and the increasing public interest in its results, make it desirable that the most efficient measures should be adopted to elevate the character of its popular literature. The tendency of careless and unscrupulous book-makers to cater to public ignorance and love of the marvellous, and to foist their crude productions upon those who are too little instructed to judge of their real quality, has hitherto been so strong as to cast discredit upon the idea of "popular science." It is highly important to counteract this evil tendency by furnishing the public with popular scientific books of a superior character. The publication of the present volume is the first step in carrying out a systematic enterprise of this kind. It initiates a series of such works on a wide range of scientific subjects, to be prepared by the leading thinkers of different countries, and known as the "International Scientific Series." It is designed to consist of compendious scientific treatises, representing the latest advances of thought upon subjects of general interest, theoretical and practical, to all classes of readers. The familiar phenomena of surrounding Nature, in their physical and chemical aspects, the knowledge of which has recently undergone marked extension or revision, will be considered in their latest interpretations. Biology, or the general science of life, which has lately come into prominence, will be explained in its leading and most important principles. The subject of mind, which, under the inductive method and on the basis of its physical accompaniments and conditions, is giving rise to a new psychology, will be treated with the fulness to which it is entitled. The laws of man's social development, or the natural history of society, which are now being studied by the scientific method, will also receive a due share of attention. While the books of this series are to deal with a wide diversity of topics, it will be a leading object of the enterprise to present the bearings of inquiry upon the higher questions of the time, and to throw the latest light of science upon the phenomena of human nature and the economy of human life.