LONDON,
January, 1906.
PREFACE TO THE SECOND EDITION
THE present edition is only a reprint of the first, with a few inaccurate expressions corrected.
E. W.
LONDON,
July, 1912.
[CONTENTS]
[INTRODUCTORY]
The origin of the present investigation, p. [1].—Its subject-matter, p. [1] sq.—Its practical usefulness, p. [2] sq.