Contents 



REPORTS ON SPECIAL RESEARCHES— Con. 

 Observations on Cruise IV of the Carnegie, 1915- 



1916 376 



Atmospheric-electric quantities measured 377 



Instrumental appliances 378 



Potential-gradient 380 



Conductivity 382 



Ionic content 35g 



Penetrating radiation 389 



Radioactive content of the atmosphere 390 



Theory of determination of emanation content 



of the atmosphere 393 



Radioactive content of the sea water 39G 



Meteorological observations 397 



Specimens of observations and of computations . . , 397 



Explanatory remarks 397 



Tables of results of atmospheric-electric observa- 

 tions on Cruise IV of the Carnegie 402 



Explanatory remarks 402 



Discussion of results of Cruise IV of the Carnegie. . 406 

 Collection of land and ocean values of atmos- 

 pheric-electric elements as obtained by various 



observers in different localities 408 



Potential-gradient 410 



Conductivity, ionic content, and air-earth cur- 

 rent-density 4H 



REPORTS ON SPECIAL RESEARCHES— Con. 



Specific ionic velocities 412 



Penetrating radiation 4J2 



Radioactive content of the air 413 



Causes of atmospheric ionization over the ocean . 414 



Diurnal variation 41Q 



Annual variation 420 



Summary of conclusions 422 



Some Discussions of the Ocean Magnetic Work, 

 1905-1916, BY L. A. Bauer and W. J. Peters. 



Corrections of magnetic charts 423 



Concerning construction of new magnetic charts. . 427 

 Preliminary values of the annual changes of the 

 magnetic elements as determined from the 



Galilee and Carnegie results, 1905-1916 430 



Data at intersections of tracks of vessels 430 



Explanatorj' remarks 430 



Preliminary average annual changes, oceans. . 432 



Annual-change data at ports 434 



Data for Gardiners Bay and Greenport, L. I. . . 434 



Absence of magnetic deviations on the Carnegie . . . 436 



Greater problems of the Earth's magnetism . . 438 



INDEX, GALILEE MAGNETIC WORK.. 4.39 



INDEX, CARNEGIE MAGNETIC WORK. 44' 



INDEX, ATMOSPHERIC-ELECTRIC REPORT. . 446 



