Fig. 12. View of recording electrometer for potential-gradient, as installed with acces- 

 sories in weatherproof box for mounting, on stern rail 



Fig. 13. Altken nuclei coiinter, used to determine the 

 number of condensation nuclei per cubic centimeter 

 in the atmosphere 



^ 25 



Fig. 14. W. C. Parkinson operating the Aitken 

 nuclei counter on the bridge 



