82 



A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 

 SECOND SERIES. n =280000. 



The n values in their relation to 5 work out similarly to the above data. 

 The two cusps are in their usual location. The green coronas correspond to 

 n= 105,000 and 113,000 nuclei, respectively, sorrewhat larger than the above 

 order of values, but not more so than the difficulties of standardization would 

 lead one to anticipate. 



The d values are difficult to interpret, as the curve is fairly uniform but for 

 the break introduced in the w g b p region. Both curves are in close agree- 

 ment, and under the circumstances it is impossible to locate the cusps and their 

 relations. 



LONG AND SHALLOW CONDENSATION CHAMBERS. 



25. Apparatus. The purpose of the present section is primarily to give 

 greater scope for the observation of the higher coronas, i. e., those of large 

 aperture. Incidentally it affords a means of testing the validity of the correc- 

 tion for subsidence, S. 



To obviate fragility of apparatus and inconvenience in the exhaustions, the 

 volume of the long vessel is suitably decreased by lessening the height. This 

 does not interfere with the work, since only a diametral section of the color 

 rings is needed while the apparatus becomes more manageable. 



The vessel is shown in the diagram, figure 2 (above, p. 58), and is (in the 

 clear) 55 cm. long, n cm. high, and 16 cm. deep in the line of vision. Less 

 height and even greater depth and length would have been preferable, but in 

 such a case the correction for subsidence becomes unwieldy. As usual, there is a 

 central brace and a lining of wet cloth, and the front and rear faces are of plate- 

 glass i inch thick. Exhaustion is effected through the wide hollow trunnion, E, 

 the other being closed and holding a thermometer, or other accessories. F is the 

 filter and P the nucleator, both attached with a cock. Rubber corks, A, A', close 

 the wide holes necessary for cleaning. The external vacuum chamber was such 

 that the pressure differences were reduced about one half on suddenly opening 

 the wide cock into the condensation chamber. There was no leakage, and the 



