No. 30. X-ray 

 nuclei. Scale 

 part, .0030 cm. 

 Fall 45 sec. 



No. 10. Air nu- 

 clei. Scale part, 

 .0012 cm. Fall 



. 30 sec. 



No. 25. X-ray 

 nuclei. Scale 

 part, .0030 cm. 

 Fall 30 sec. 



No. 27. X-rai 

 nuclei. Scali 

 part, .0030 cm 

 Fall 1 5 sec. Dev 

 in negative. 



No. 23. X-ra; 

 nuclei. Scale 

 part, .0030 cm 

 Fall 30 sec. 



No. 9. P nuclei 

 Scale part, .001: 

 cm. Fall 45 

 sec. 



No. 22. Scale 

 part, .0030 cm. 

 "Craters." Fall 

 30 sec. X-ray 

 nuclei. 



No. 4. P nuclei. 

 Scale part, .0044 

 cm. Fall 20 sec. 



FIGURE 10. MICRO-PHOTOGRAPHS OF FOG PARTICLES, PRECIPITATED ON PERSISTENT NUCLEI USUALLY 

 PRODUCED BY THE X-RAYS IN DUST-FREE AIR. 



116 



