Typographical errors noticed during the preparation of this text have been underlined like this. A list has also been placed at the end.

PREFACE.

In the following account of the life and works of Sir William Herschel, I have been obliged to depend strictly upon data already in print—the Memoir of his sister, his own scientific writings and the memoirs and diaries of his cotemporaries. The review of his published works will, I trust, be of use. It is based upon a careful study of all his papers in the Philosophical Transactions and elsewhere.

A life of Herschel which shall be satisfactory in every particular can only be written after a full examination of the materials which are preserved at the family seat in England; but as two generations have passed since his death, and as no biography yet exists which approaches to completeness, no apology seems to me to be needed for a conscientious attempt to make the best use of the scanty material which we do possess.

This study will, I trust, serve to exhibit so much of his life as belongs to the whole public. His private life belongs to his family, until the time is come to let the world know more of the greatest of practical astronomers and of the inner life of one of its most profound philosophers,—of a great and ardent mind, whose achievements are and will remain the glory of England.