Institution of Civil Engineers. 421 



gives a circumstantial account of the progress and course of various 

 gales which came under his observation during that period, and from 

 which he infers the existence of a steady connexion between the pre- 

 vailing winds of this region and the movements of the barometer, and 

 enters into an inquiry into the mode in which that instrument is affect- 

 ed by them. The extensive valley of the St. Lawrence is bounded at 

 its lower part, for a distance of nearly 500 miles, by ranges of hills, 

 rising on each side to a considerable elevation. Within this space 

 the ordinary winds follow the course of the river ; and in almost 

 every instance where they approach from windward, the barometer 

 rises with them ; and when, on the other hand, the wind approaches 

 from leeward, the barometer not only falls before the arrival of the 

 wind, but continues to fall until it has subsided. An appendix is 

 subjoined, containing extracts from the tabular register of the baro- 

 meter and winds at various points in the valley of the St. Lawrence, 

 during the years 1834 and 1835, accompanied by remarks on differ- 

 ent points deserving notice in particular cases. 



' On the Elliptic Polarization of Light by Reflexion from Metallic 

 Surfaces,' by the Rev. Baden Powell. — In a former paper, published 

 in the Philosophical Transactions for 1843, the author gave an ac- 

 count of the observations he had made on the phenomena of elliptic 

 polarization by reflexion from certain metallic surfaces, but with re- 

 ference only to one class of comparative results. He has since pur- 

 sued the inquiry into other relations besides those at first contem- 

 plated ; and the present paper is devoted to the details of these new 

 observations, obtained by varying the inclination of the incident rays 

 and the position of the plane of analyzation, and by employing dif- 

 ferent metals as the reflecting surfaces. By the application of the 

 undulatory theory of light to the circumstances of the experiments 

 and the resulting phenomena, the law of metallic retardation is made 

 the subject of analytic investigation. A polariscope of peculiar con- 

 struction, of which a description is given at the conclusion of the 

 paper, was employed in the experiments ; and tables are subjoined 

 of the numerical results of the observations. — Ibid, July 5, 1845. 



Institution of Civil Engineers. — June 10. — Sir John Rennie, 

 President, in the chair. — The paper read was by Mr. J. Stirling, and 



