230 ROCHESTER ACADEMY OF SCIENCE. [April I4, 



the eastern and northern quadrants of the storm, are brought inland, 

 and are easily precipitated by elevation, radiation and mixture with 

 cold air found over the lakes and along the borders. This is the 

 mechanics of every heavy snowstorm whose history has been examined 

 at this place. 



CLOUDINESS. 



In cloudiness, Rochester easily holds the lead, so far as records 

 are available. It is great in amount and remarkably evenly distributed 

 through the year. It is greatest in December with a normal of 83 

 per cent. , and least in August with an a\erage of 44 per cent. , and 

 the average for the year is 61 per cent. Compared with some other 

 places, we find the same figures to be at Boston, 56 per cent, in 

 December, 45 per cent, in August, and 51 per cent, for the year; 

 Yankton, S. D. , 51 per cent, in March, 39 in September, and 45 

 per cent. ; San Francisco, 48 per cent, in January, 32 per cent, in 

 October, and 42 per cent.; Portland, Ore., 72 per cent, in January, 

 35 per cent, in August, and 59 per cent. For the spring : at Rochester, 

 the cloudiness is 58 per cent. ; Boston, 54 per cent. ; Yankton, 52 per 

 cent. ; San Francisco, 43 per cent. ; Portland, 64 per cent. The 

 summer : Rochester, 46 per cent. ; Boston, 46 per cent. ; Yankton, 

 42 per cent.; San Francisco, 43 per cent.; Portland, 64 per cent. 

 Autumn: Rochester, 62 per cent.; Boston, 51 per cent.; Yankton, 

 41 per cent.; San Francisco, 35 per cent.; Portland, 55 per cent. 

 Winter : Rochester, 78 per cent. ; Boston, 53 per cent. ; Yankton, 

 47 per cent.; San Francisco, 47 per cent., Portland, 72 per cent. 

 Allowing 10 per cent, for sunshine through thin clouds and adding 

 the complement of the cloudiness sunshine is 49 per cent, of the 

 possible at Rochester, 59 per cent, at Boston, 65 per cent, at Yank- 

 ton, 68 per cent, at San Francisco and 51 per cent, at Portland. 

 Once during the past twenty-five years the cloudiness has been 100 

 percent, for ten days, once 98 per cent., twice 96 per cent, and 

 eleven times above 90 per cent., all except three occurring during the 

 winter decades. The greatest for 30 days is 91 per cent, ending 

 February 3, 1886, and the least 28 per cent, ending October 6, 1891. 



WINDS. 



In wind velocities Rochester is believed to hold about an average 

 position. The most marked feature is found in the absence of 

 tornadoes and very severe storms. 



Remarks were made in discussion (jf tlie paper by Emil Kuichling, 

 Professor A. L. Baker, J. E. Putnam, the President, and the author. 



