A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



103 



Various modifications of this apparatus were then used, among them cap- 

 sule forms, figures 2 and 3, similar to Aitken's, but containing a very thin plate 

 of glass or mica or celluloid slightly raised above the base on pellets of wax. 

 It was supposed that this would counteract the tendency of the drops to vanish 

 by evaporation from the warmer glass surface. Capillary metallic tubes led to 

 the curl aneroid, a, the filter, /, and to the cock for influx of air, the only large 



FIGURE ia. THE SAME MOUNTED IN CONDENSATION CHAMBER. 



tube being the exhaust pipe, e. Condensation again occurred as a microscop- 

 ically granular deposit spontaneously on the raised surface, under all circum- 

 stances, and the experiments were failures. After oiling the filmy mica surface, 

 p, however, droplets were often seen to fall and either to stick fast or to float. 

 These could at times be counted (2000-5600 per cub. cm.) ; but the rapid evan- 



FIGURE 2. CAPSULE. PLAN. 



FIGURE 3. SAME. SECTIONAL ELEVATION. 



escence of precipitated droplets and the failure of all attempts to reach systematic 

 results induced me to abandon the capsule. 



I therefore returned to the apparatus in figure i, using at 5 a plate of thin 

 microscopic glass covered with a thin film of oil and exposed in the capacious 



