FIGURES 1 - 17 



TITLE Page 



Fig. 1. Mean diurnal variation of potential-gradient for three-month periods from 



observations on board the Carnegie . 1915-1921 and 1928-1929 ' 163 



Fig. 2. Daily mean values of conductivity from recorder apparatus CA8A, Carnegie , cruise 

 Vn, from measurements in the central Pacific Ocean, September 5 to November 

 i8, 1929 163 



Fig. 3. Diurnal variation in positive electrical conductivity over the central Pacific Ocean 



from continuous registrations on the Carnegie , cruise Vn, September to November 



1929 164 



Fig. 4. Diurnal variation in negative electrical conductivity over the central Pacific Ocean 



from continuous registrations on the Carnegie , cruise VTl, September to November 



1929 164 



Fig. 5. Electrical conductivity and potential-gradient over the central Pacific Ocean from 



continuous registrations on the Carnegie , cruise VII, October and November 1929 165 



Fig. 6. Diurnal variation in positive electrical conductivity, Carnegie , cruise VTI; (A) Over 

 the southeastern Pacific Ocean, November 1928 to February 1929, (B) Over the 

 central Pacific Ocean, September to November 1929 165 



Fig. 7. Electrical conductivity and potential gradient over the central Pacific Ocean from 



• manual observations on the Carnegie , cruise VI, April to August 1921 166 



Fig. 8. Air -conductivity records on the Carnegie : (a) X + , approaching Honolulu, September 

 23, 1929; (b) A., in Honolulu harbor, September 24, 1929; (c) \ + , record at sea, 

 October 30, 1929, disturbed by bad weather 167 



Fig. 9. Change in ratio A +/X - with change in potential-gradient. Points are daily means of 

 recorder values of potential-gradient and corresponding ratios of daily means of 

 recorder values of A + and A-. Carnegie , cruise VII, October 5 to November 12, 

 1929 168 



Fig.lO. Change in ratio A+/A- with change in potential-gradient, using eye-reading measure- 

 ments of conductivity obtained July 28, 1928 to October 9, 1928 in the Atlantic Ocean 

 and November 5, 1928 to July 28, 1929, in the Pacific Ocean 168 



Fig. 11. Frequency curves of computed mobilities, for positive and negative ions, k+ and k., 



for cruises IV, VI, and VII of the Carnegie . 1915-1929 169 



Fig.l2A. Variation in conductivity and ion content with computed mobility, from combined data 

 of cruises IV and VI, using values of both positive and negative components; frequency 

 curve for mobility data at bottom 170 



Fig.l2B. Variation in conductivity and ion content with computed mobility, from eye-reading 

 data of cruise VTI (May 1928 to July 1929), using values of both positive and negative 

 components; frequency curve for mobility data at bottom 171 



Fig.l3. Variation in conductivity and ion-content with computed mobility, after conductivity 

 recording began on cruise VII (September to November, 1929), using values of 

 both positive and negative components; frequency curve for mobility data at bottom 172 



Fig.l4. Diurnal variation in computed air-earth current density, Carnegie , cruise VII, August 



1928 to November 1929 173 



Fig. 15. Variation in computed air -earth current density with change in latitude 174 



Fig. 16. Wind force (Beaufort) and direction and condensation-nuclei content of the air from 



measurements aboard the Carnegie , cruise VII, between Hamburg and Reykjavik 174 



Fig.l7. Diurnal variation in condensation nuclei over the oceans, from cruise VH data of the 



Carnegie 175 



161 



