148 



A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



distribution of the nucleation observed. It is to be remembered, moreover, 

 that the true law of reduction is periodic, and unless the periodicity is fully 

 worked out for the small coronas, the temperature correction has little meaning. 

 It is because of this complexity that the tables are very specific as to the color 

 type of the coronas, their size, the temperature of the fog particles, etc. In 

 any special case, therefore, the rigorous reduction (if of interest) may be at- 

 tempted, but at present there is no call for it. 



As to the accuracy of the results so far as the readings are concerned, an 

 error of 2000 to 3000 nuclei per cubic centimeter is unnecessary in the ex- 

 treme case of large coronas; whereas the whole range of variation is about 

 from 2000 to above 100,000. For the small coronas the reading is correspond- 

 ingly sharp, and the same is true if a larger goniometer is used. 



TABLE i. Continuous record of atmospheric nucleation from March 15, 

 1903, to November i, 1904. The time (t) is given in hours and tenths of an 

 hour, the temperature of the fog chamber in degrees centigrade, the local at- 

 mospheric temperature (approximate) in degrees Fahrenheit. The aperture 

 of the coronas is s, where the angular aperture is ^ = 2 sin 5/39, as the arms of 

 the goniometer are 19.5 cm. long. The last column but one shows the number 

 of nuclei, n, per cubic centimeter of air, using the table in Chapter VII, 26, 

 for the reduction from 5 to n. Temperature corrections were not applied. 

 The pressure difference was uniformly 6p=i'j cm. of mercury. The distances 

 of the eye and the source of light were 85 cm. and 250 cm. (i 13), on opposite 

 sides of the condensation chamber. The weather abbreviations are f fair, f 

 partly fair, c' partly cloudy, c cloudy, R' slight rain, R rain, Sn snow, S sun, 

 etc. The coronal color abbreviations are c (crimson) deep red, r orange red, 

 br brown, o orange, y yellow, g green, b blue, v violet, p purple, etc. A ver- 

 tical line denotes an indeterminate color, as w r | g ; an accent an approach to 

 the color, as r' reddish; a capital, a deep dark color, as B deep blue, etc. Mixed 

 colors are written together, as bg, blue-green, or, orange-red. Subsidence 

 measurements when entered (November, 1903) are usually abbreviated a/b, 

 meaning that a seconds are required for a fall of the fog line of b centimeters. 

 Sometimes the abbreviation is b/a, as will be stated (April, 1904). 



