'No natural phenomenon can be adequately studied in itself alone-but, to be
understood, it must be considered as it stands connected with all Nature'

PREFACE.

EIGHTEEN YEARS have elapsed since the last or ninth edition of the 'Connexion of the Physical Sciences' was published. During that time rapid advances have been made in all branches of science; and it has been a task of no slight difficulty to correct a classical work of this kind, and bring it up to the knowledge of the day, while preserving intact its original form and the impress of the author's mind.

If, however, the book ceased to be essentially Mrs. Somerville's, its value would be destroyed, and on this account every passage in which her own views are expressed has been carefully preserved, even if somewhat antiquated. Facts and figures, on the other hand, have been carefully revised and corrected in accordance with modern authorities, and those passages which remain untouched have been compared, whenever this was possible, with the original works consulted by Mrs. Somerville.

In many cases it has been absolutely necessary to add much new matter; and, as it was not easy to indicate these passages in the work itself, a list of the most important of them is given at the end of the Preface.

The notes and plates, which were formerly at the end of the volume, have now been transferred to the pages to which they refer; in all other respects the arrangement of the work is unaltered.

In conclusion, the Editor wishes to acknowledge her great obligations to Professor Clerk-Maxwell, Dr. Tyndall, the Rev. R. Main, Mr. H. Russell, Herr Marth, Mr. Knobel, and many other scientific men, who have most kindly given her help and information.

January 1877.