derived much aid from the Répertoire d'Optique Moderne of the Abbè Moigno,—a work which contains a full analysis, and critical discussion, of most of the recent researches in Optics. He has also to acknowledge his obligations to M. Moigno, for the favourable introduction of the former edition of the present work, in the pages of the "Repertoire," to the notice of Continental readers.
The form of Lectures has been abandoned; but the author fears that the style still retains more of the traces of the lecture-room than is consistent with a formal scientific treatise. His only aim has been to present, to those who were conversant with the elements of Mathematics, a clear and connected view of his attractive subject; and he has been compelled, by this limitation, to confine himself in many cases (as in all that relates to the Dynamics of Light) to a general account of methods, and of their results. Those who desire a more exact acquaintance with the science will, of course, study it in Sir John Herschel's Essay on Light, and in Mr. Airy's Tract on the Undulatory Theory of Optics.