238 



FIG. 1. 



T^ro p hotographs of the same bubble In water under low 

 surface pressure. 



(1) at an early stage, when it is smooth and spherical; 



(2) at a later stage, when the bubble has become 



pitted by boiling near the surface. 



FIG. 4. 



PIG. 5. 



FIO. 6. 



Photographs of bubbles in oil under vacuum , showing how 

 the bubble becomes distorted as its a^ e increases. 



Fig. 4. Spherical bubble, age 25 mlllisec. 



Fig. 5. Bubble with pronounced flattening on underbid*, 



age 50 mil li sec. 

 Fig. 6. llushro<»-shaped bubble, age 80 mlllisec. 



