PREFACE TO THE FIRST EDITION.

The greater part of the following papers was originally written for delivery in the form of popular lectures. They were then published in a University Magazine, the Light Blue; and having met with considerable success in both these ways, they have now, at the suggestion of several friends, scientific and non-scientific, been partially rewritten and enlarged into their present form. I have endeavoured, however, to keep their original object unaltered, and to write nothing which would would not be at once interesting and intelligible to non-scientific readers. There is no lack of systematic, and yet easy works of Astronomy, such as those of Sir John Herschel, M. Arago, and W. Norman Lockyer; and I have, therefore, made it my object not so much to instruct as to entertain, and possibly in some cases to inspire a taste which might lead to the further

most

fascinating study.

prosecution of a This must be my apology for passing over entirely many important parts of the subject, and simply selecting a few points here and there which seem to afford scope for striking or amusing amplification.

I have to thank two very distinguished Members of my own College, Sir William Thomson and Professor Tait, for kind suggestions and advice.

PETERHOUSE,

December, 1873

The kind reception which the first edition of these papers met with from the public and the press encourages me to think that their object has been in some measure attained. I regret that the pressure of other work has so long delayed the appearance of the second edition. It contains a few alterations and additions.

August, 1875.