EFFECT OF VAPOR PRESSURE. 23 



that the total variation of pressure to bring out the coronal phenomenon 

 does not much exceed 3 cm., and that the observations below will be 

 made within a single centimeter, the precipitation of moisture may be 

 treated as depending on T/T I; the ratio of the initial and the final tem- 

 perature of adiabatic cooling if the former is nearly constant and if the 

 same medium is retained, though the case is in reality more complicated. 

 These data are also given in table 9 and have been inserted in fig. 7. 



FIG. 7. Nucleation found at different drops of pressure. Second extreme case. 



The graphs III, IV, and V are now even more coincident, whereas I 

 and II, F and IF differ from each other and from III and V in the same 

 sense as above. Hence, apart from barometric pressure, some other 

 cause must have influenced these nucleations. 



