TABLES OF RESULTS OF ATMOSPHERIC-ELECTRIC OBSERVATIONS ON 



CRUISE IV OF THE CARNEGIE. 



EXPLANATORY REMARKS. 



The following definitions will explain the meanings to be attached to the symbols at 

 the heads of the tables: 



P = atmospheric pressure in millimeters of mercury, corrected for zero error of 



barometer, temperature and latitude; 

 7" = temperature, in degrees centigrade; 

 H = relative humidity, expressed as a percentage ; 

 n+ and n_ = respectively, the numbers of positive and negative ions per c.c. ; 

 X+andX_= unipolar conductivities in e.s.tj.XIQ-S for positive and negative ions 

 respectively ; 

 v+ and r_ = specific ionic velocities, in centimeters per second per volt per centimeter, 

 for positive and negative ions respectively; 

 X = potential-gradient in volts per meter; 

 i = air-earth current density in e.s.xj.XIO"^; 

 72 = rate of production of pairs of ions per c.c. per second in a closed copper 



vessel of 27 Uters capacity ; 

 rjo = number of pairs of ions produced per second, in the ionization chamber of 

 the radioactive content apparatus, 3 minutes after the completion of the 

 deposition, and corresponding to the active material which would be 

 deposited in an air-flow of 1 c. c. per second; and 

 Q = radium-emanation content in curies XlO"^^ per cubic meter. Values of Q 

 less than 0.05 are recorded as 0.0. There is, of course, no proportionality 

 between rjo and Q, since the latter quantity involves the shapes of the 

 experimental decay-curve. 

 The wind strengths are estimated on the Beaufort scale, and the weather indications 

 according to the U. S. Weather Bureau's instructions for marine observers; the degree 

 of cloudiness is indicated by the numbers to 10. 



The quantities under the heading Q have been obtained as explamed on pages 393-396. 

 The decay curves for the sets of daily observations have been divided into groups of 

 about 10, and the mean curve has been constructed for each group. These mean curves 

 have then been used for the calculation of the corresponding values of Q. The braces 

 under Q in the tables serve to indicate the periods to which correspond the values 

 recorded between them. 



On December 9, 1916, the Carnegie crossed the 180-degree meridian, which explains 

 why this date appears twice in the tables. 



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