Mr. J. Barton on the Iitflexion of Light* 263 



April 5, South ; May 8, North-west; April 14, South; De- 

 cember 27, South. 



In the course of the year 1830, there were at St. Petersburg: 

 — 90 days of rain ; 68 days of snow; 10 days of thunder; 

 58 days during which the sky was entirely covered from 

 morning till night; 218 days during which the sky was 

 cloudy during the greatest part of the day; 143 days of fog 

 (these fogs were commonly produced in the morning, but less 

 frequently in the evening, and they very seldom lasted beyond 

 noon); and 28 days during which the sky was entirely clear 

 from morning till night. 



The last frost took place on the 4th of May. — The first frost 

 on the 14th of October. 



The thermometer rose above zero, 



For the first time on the 27th of February ; — and for the last 

 time on the 28th of December. 



The day of the flood on the Neva, 21st of April. — The day 

 of its being shut up, 1st of December. 



Aurorce Boreales. — These meteors appeared on the evenings 

 of the following days:— Feb. 24th; March 18th; May 5th; 

 Sept. 13, 17, 18, and 19; Oct. 18 and 22; and Dec. 8 and 15. 



XLIII. On the Inflexion of Light. By John Barton, Esq.* 



^OME time ago I had the honour to submit to the Royal 

 ^ Society an account of a variety of experiments and obser- 

 vations on the inflexion of light, which seemed to me strongly 

 to indicate that light consists of material particles, endued 

 with a force of mutual repulsionf. I have since had the sa- 

 tisfaction to find that the possibility of explaining the phae- 

 nomena of inflexion by the help of the same principle had 

 suggested itself to the mind of Sir David Brewster :f. In the 

 paper just mentioned, I did not enter into any discussion re- 

 specting the theories of Young and Fresnel, — contenting myself 

 with a simple detail of the results of my own experiments, ac- 

 companied by such explanatory observations as seemed need- 

 ful to connect them together, and render them intelligible; 

 but I wish now to state some considerations which appear to 

 me to be decisive against those theories. 



The fundamental principle common to them both is this : — 

 If two equal waves, moving in opposite directions, come into 

 collision, they will destroy each other, and all further move- 

 ment will cease ; whereas, if they coincide in their direction, 



* Communicated by the Author. 



f An abstract of the paper here alluded to was given in Phil. Mag. and 

 Annals, N.S. vol. x. p. 300: it has also been noticed by Prof. Powell, in 

 vol. xi. p. 2.— Edit. % Life of Newton, p. 105. 



