has succeeded in deducing, as parts of one and the same general theory, not only the laws of propagation in the same medium, pre- viously discovered by Fresnel, but also the laws of reflexion which take place at the bounding surface of any two media, already disco- vered by himself and M. Newmann. TJie same theory has likewise led to the demonstration of those physical principles, which had been assumed in the former paper. It has shown that the vis viva is ne- cessarily preserved, in the passage of light from one medium into another ; that the resultants of the vibrations are the same in the two media ; and finally, that the vibrations themselves are parallel to the plane of polarization.
This seems to be the most advanced point to which the physical theory of light, in its present form, is capable of being pushed ; and it is only by the addition of new physical principles^ and further in- sight into the constitution of the luminiferous medium, that any ul- terior progress can be expected.
Mr. Fox Talbot. The many important discoveries made by you in Photography, discoveries to which I have adverted when addressing the Society on another occasion, discoveries which seem, with those of an ana- logous nature made by a Neipse and a Daguerre, to open to us the vista of discoveries still more vast and curious, undoubtedly well en- title you to the honour of the Rumford Medal at our hands. Your papers, indeed, have been so great an ornament to our volumes, that we can never sufficiently express our thanks to you for them. I trust that you will not desert so promising a line of inquiry, and that our Transactions may receive from you still greater acquisitions of knowledge in the path which is traced by light itself.
Mr. Bowman.
It must be always satisfactory for a President of the Royal Society to present to one of your profession a Royal Medal for labours which have as their instruments, the assiduous application of the noblest faculties of reason — as their immediate purpose, the knowledge of the sublime truths contained in the wonderful adaptations of the organs of created beings — and as their ultimate end, the cure of disease, the al- leviation of agony, and the prolongation of human life. Gentlemen of your own valuable profession have given their testimony to the import- ance of your discoveries, and the Council feels pleasure in rewarding your zeal and talents. To you, and all who, like you, are employed in these noble pursuits, all here will say with me, may God prosper your labours to His glory and to the happiness of His creatures.
Mr. Daniell.
The continued intercourse that I have had with you in the Coun- cil of the Royal Society increases the pleasure which I experience in giving into your hands this Medal. Electrical Chemistry, at all times of great importance as giving us an insight into the most re- condite laws of nature, has now acquired additional interest by the
