136 



OCEAN ATMOSPHERIC -ELECTRIC RESULTS 



Table 1. Summary of atmospheric-electric potential-gradient records obtained on cruise VII of the 

 Carnegie and of factors affecting the potential-gradient 



Month 



Days 

 at 

 sea 



Complete 



24 -hour 



record 



Partial 

 24-hour 

 record 



Bad 

 weather 



Negative 

 potential 



Instrumental 

 defects 



Engine 

 running 



Accepted 



fair-weather 



days 



9 



9 



1 



19 



17 



10 

 18 



8 



3 

 19 



7 

 22 





 10 

 15 

 14 



11 

 7 

 7 

 6 

 4 



2 

 2 

 5 

 6 

 7 

 4 

 5 

 

 i 

 12 

 4 



11 

 7 

 6 



10 

 6 



2 



4 

 4 

 7 



17 

 3 



24 

 



.3 



20 

 4 



4 

 6 

 6 

 6 

 4 





 

 1 

 6 

 7 

 1 

 6 

 

 

 8 

 4 



10 



4 

 9 

 9 

 7 



3 

 4 



12 

 5 

 1 

 3 

 2 

 

 8 



12 

 



5 

 

 2 

 

 











11 



6 



2 



9 











8 



11 



10 



6 

 9 

 1 

 12 

 9 



8 

 12 

 5 

 1 

 7 

 

 

 

 1 

 6 

 5 



Totals 317a 



181b 



86C 



128 



59 



89 



64 



82 



^On 46 days at sea no record was obtained because of instrumental defects and on 4 additional days no 

 record was obtained because the main engine was running. ^Negative potential occurred on 21 complete 

 days. ^Parts of 43 days at sea were lost because of instrumental defects, of 9 others because the engine 

 was running, of 27 days more because of bad weather, and of 7 days because of the ship's arrival or de- 

 parture from various ports. 



Table 2. Summary of Fourier analyses of diurnal variation of the atmospheric potential-gradient (P) from 

 Carnegie observations during 1915-21* (cruises IV, V, and VI) and during 1928-29 (cruise VII) 



Cruises 



Grouping 



Phase-angles 



<t>\ <t>2 <^3 "^4 



Amplitudes 



C2 



C4 



Ratio 

 C2/ci 



GMT 

 Maxi- 

 mum 



Year 



132 192 240 195 344 20.3 15 6.3 



2.3 



1.6 1 



0.31 17.2 



^hese are finally revised values, correcting values published in Volume V of the Researches of the Depart- 

 ment of Terrestrial Magnetism (p. 397). "There were no records obtained at sea during June or July 1928 and 

 no quiet days in June and July 1929. 



times of maximum of the twenty-four-hour wave com- 

 pare excellently for the two sets of data. Very good 

 agreement may be noted also for practically all the 

 other items in the two groups. 



By the utilization of recording apparatus, potential- 

 gradient measurements on cruise VII of the Carnegie 

 were increased several fold in comparison with previous 



cruisesand the possibility of obtaining continuous series 

 instead of isolated sets of observations greatly enhanced 

 the value of the work. It is to be hoped that oceanographic 

 or other scientific expeditions planned for the future may 

 include recording potential-gradient apparatus similar to 

 that employed on the Carnegie . 



