112 NUCLEATION OF THE UNCONTAMINATED ATMOSPHERE. 



TABLE 60. Number of nuclei (n) per cubic centimeter in the atmosphere of Provi- 

 dence, R. I., from November i, 1904, to May i, 1905. 



[Weather: C cloudy, CF partly cloudy, F fair. Coronal colors (r red, b blue, p purple, 

 w white, o orange, y 3'ellow, g green, br brown) are given from the center outward. An accent 

 denotes an approach to the color (y' yellowish); a perpendicular line, a thin ring of indetermi- 

 nable color. If (j> is the angular diameter of the corona measured to the outside of the first red 

 ring, 2 sin 0/2 = 5/30.] 



