ELEMENTARY TREATISE ON THE WAVE-THEORY OF LIGHT. BY HUMPHREY LLOYD, D. D., D. C. L.; F. R. SS. L. & E.; V. P. R. I.A.; FELLOW OF TRINITY COLLEGE, DUBLIN. Second Edition, with Additions. LONDON: LONGMAN, BROWN, GREEN, LONGMANS, AND ROBERTS. 1857. 185. a. 4. ADVERTISEMENT TO THE SECOND EDITION. THE former edition of this little work was given to the public in the shape of Lectures, as delivered, in compliance with the regulations of the Chair which the author then occupied, and without any expectation that its use would extend much beyond the circle of his immediate hearers. It has, however, found its way elsewhere; and the author has been urged, by some of his fellow-labourers in other Universities, to reprint it. With this request he could not but comply; and he trusts that the delay in acceding to it may be excused to those who made it, by the desire of the author to render the work more deserving of their favourable estimation. In the present edition some account is given of the more important discoveries in Physical Optics, which have been made since the publication of the former. In preparing these additions, the author has b |