338 



CARNEGIE INSTITUTION OF WASHINGTON. 



No marked variation of the atmospheric-electric elements with temperature 

 or humidity was found ; however, an indication is shown of a variation of the 

 conductivity with latitude, a maximum for the latitudes involved occurring in 

 the neighborhood of 50° north. These conclusions with regard to the varia- 

 tion of the elements with season, latitude, etc., must be looked upon as tenta- 

 tive, owing to the small number of data involved. A comparison has been 

 made of the mean values of the conductivity for the several sections of the 

 cruise, with the values to be expected as a result of the measured radioactive 



content. The results are given in table 5; they have been calculated by 

 reducing the measured radioactive content to Elster and Geitel units and then 

 making use of an empirical relation obtained by Kurz for the rate of production 

 of ions per cubic centimeter corresponding to 1 Elster and Geitel unit. In the 

 table, q represents the rate of production of ions per cubic centimeter owing to 

 the radioactive material, and the number of ions (n) per cubic centimeter of 

 either sign has been calculated from the expression n'^ = q/a, where a is the 

 coefficient of recombination of the ions and is taken as 1.56X10~^ The con- 

 ductivity is taken as 2nev, v being the specific velocity of the ions. The value 

 of V has been taken as 1.6 cm. per second per volt per centimeter for each sign 

 of ions. 



Table 5. 



In the observations in Long Island Sound, n was measured directly for each 

 kind of ion, and so it became possible there to compare the measured value of 

 n,-\-n_ with the calculated 2n without introducing the specific velocity of 

 the ions. In the above calculated values the effect of the penetrating radia- 

 tion from the active material in the sea has been neglected. This effect is very 

 small, however. It will be seen that while in the Atlantic Ocean the radio- 

 active material is sufficient to account for an appreciable fraction of the con- 

 ductivity, it is by no means sufficient to account for all of it. It must further 

 be borne in mind that in so far as many of the ions produced by the radioactive 



