328 



CARNEGIE INSTITUTION OF WASHINGTON. 



Caribbean Sea, and the remainder just to the north of the West Indies. 

 They thus correspond to a region of the sea near to land, and while they are 

 in harmony Avith the results of former ocean observations in indicating excep- 

 tionally small values for the conductivity and ionic content in such regions, 

 they are not to be taken as typically representative of ocean values. 



Table 5 shows the observations grouped according to the scheme indicated 

 in the first column of the table. The values of n+, n_, X-f-, X_, X, and i 

 are here reduced to daily mean values with the aid of the diurnal-variation 

 results obtained throughout the cruise, and on the basis of the rough assump- 

 tion that the diurnal variations of n_, X^-, and X_, are the same as that of 

 n+. It was further assumed that the mean diurnal-variation curves for the 

 whole cruise are sufficiently appropriate ones to use for the purposes of the 

 reductions. R showed no diurnal variation, and so needed no reduction. 

 Except in the case of the radioactive content, there is a very close agreement 



T.\BLE 5. — Mean values of almospheric-electric elements, corrected for diurnal variation. 



between the corresponding values for the Pacific and sub-Antarctic Oceans. 

 The mean value 113 volts per meter, for the potential-gradient, is in general 

 agreement with former ocean determination and is of the same order of 

 magnitude as the mean of several land values, 151 volts per m.eter. 



Table 6 shows a comparison of the results for the Carnegie's fourth cruise 

 with the means of a large number of former ocean and land determinations. 

 The agreement between the fourth cruise values and the others quoted is, in 

 general, remarkably close, and, in particular, the former values confirm the 

 important conclusion that the ionization over the ocean is practically the 

 same as that over the land. The ocean values of v+ and v- are somewhat 



