Proceedirigs of the British Association. 323 



accuracy, and of the obsen'^ers, (all natives of India,) Mr. C. re- 

 marks that after the first difficulty of instructing them is sur- 

 mounted, their patient, diligent and temperate habits peculiarly 

 fit them for the office here required of them, and I have always 

 found those who have been selected for the duty full as trustwor- 

 thy as any class of persons probably, to whom such observations 

 are usually intrusted. For the two years ending June 30, 1838, 

 the mean temperature of the station was 78°. 79 : the mean dew 

 point 71°. 78. The barometric registers give, by a mean of all 

 the diurnal semi-oscillations, the following results: 



Fall between 10 A. M. and 4 P. M. . . .109 inch. 

 Hise " 4 P. M. and 10 A. M. . . .108 " 



Fall " 10 A. M. and 4 A. M. . . .071 " 

 Rise " 4 A. M. and 10 A. M. . . .073 " 



Times of maxima^ between the hours of 9 and 10 morning 

 and evening. Times of minima, between those of 3 and 4 after- 

 noon and morning. 



Mr. Scott Rnssell read the report of the Committee on Waves. 

 All the objects confided to this committee, (consisting of Sir John 

 Robinson and himself,) having been fully accomplished, the re- 

 port now presented was to be considered as final. That part of 

 the duties of the committee which related to the connexion of 

 the phenomena of waves with the resistance of fluids to solids, 

 had devolved upon them under a separate name, as the committee 

 on forms of vessels, and would be reported under a separate head. 

 The wave form of vessel, however, had been now proved to pos- 

 sess so many advantages, that its use seemed likely to become 

 general, and thus a great change would be effected in naval ar- 

 chitecture. Prof. Kelland read a communication on the theory 

 of waves. — Sir D. Brewster communicated a paper on Prof. Pow- 

 ell's measures of the indices of refraction for the lines G and H 

 in the spectrum ; and Prof. Powell one on an experiment of in- 

 terference of light. 



On a blue sun seen at Bermuda. Sir D. Brewster communi- 

 cated a letter from Lieut. Col. Reid, governor of the Bermudas, 

 covering a letter from Dr. A. .W. Harvey, of Bermuda, who states 

 that on the 11th and 12th August, 1831, immediately after a hur- 

 ricane which devastated Barbadoes, the sun appeared of a bluish 

 color, and its light was unusually dim. This was owing, as Sir 

 D. Brewster imagined, to the interposition between the sun and 



