PREFACE 



Of the 110,000 nautical miles planned for the seventh 

 cruise of the nonmagnetic ship Carnegie of the Carnegie 

 Institution of Washington, nearly one-half had been com- 

 pleted on her arrival at Apia, November 28, 1929. The 

 extensive program of observation in terrestrial magnet- 

 ism, terrestrial electricity, chemical oceanography, 

 physical oceanography, marine biology, and marine me- 

 teorology was being carried out in virtually every detail. 

 Practical techniques and instrumental appliances for 

 oceanographic work on a sailing vessel had been most 

 successfully developed by Captain J. P. Ault, master and 

 chief of the scientific personnel, and his colleagues. The 

 high standards established under the energetic and re- 

 sourceful leadership of Dr. Louis A. Bauer and his co- 

 workers were maintained, and the achievements which 

 had marked the previous work of the Carnegie extended. 



But this cruise was tragically the last of the seven 

 great adventures represented by the world cruises of the 

 vessel. Early in the afternoon of November 29, 1929, 

 while she was in the harbor at Apia completing the storage 

 of 2000 gallons of gasoline, there was an explosion as a 

 result of which CaptauiAult and cabin boy Anthony Kolar 

 lost their lives, five officers and seamen were injured, 

 and the vessel with all her equipment was destroyed. 



In 376 days at sea nearly 45,000 nautical miles had 

 been covered (see map, p. iv). In addition to the exten- 

 sive magnetic and atmospheric-electric observations, a 

 great number of data and marine collections had been 

 obtained in the fields of chemistry, physics, and biology, 

 including bottom samples and depth determinations. 

 These observations were made at 162 oceanographic sta- 

 tions at an average distance apart of 300 nautical miles. 

 At each station, salinities and temperatures were ob- 

 tained at depths of 0, 5, 25, 50, 75, 100, 200, 300, 400, 

 500, 700, 1000, 1500, etc., meters, down to the bottomor 

 to a maximum of 6000 meters, and complete physical and 

 chemical determinations were made. Biological sam- 

 plesto the number of 1014 were obtained both by net and 

 by pump, usually at 0, 50, and 100 meters. Numerous 

 physical and chemical data were obtained at the surface. 

 Sonic depths were determined at 1500 points and bottom 

 samples were obtained at 87 points. Since, in accord- 

 ance with the established policy of the Department of 

 Terrestrial Magnetism, all observational data and ma- 

 terials were forwarded regularly to Washington from 

 each port of call, the records of only one observation 

 were lost with the ship, namely, a depth determination 

 on the short leg between Pago Pago and Apia. 



The compilations of, and reports on, the scientific 

 results obtained during this last cruise of the Carnegie 

 are being published under the classifications Physical 

 Oceanography, Chemical Oceanography, Meteorology, 

 and Biology, in a series numbered, under each subject, 

 I, II, and ni, etc. 



A general account of the expedition has been prepared 

 and published by J.Harland Paul, ship's surgeon and ob- 

 server, under the title The last cruise of the Carnegie , 

 and contains a brief chapter on the previous cruises of 

 the Carnegie , a description of the vessel and her equip- 

 ment, and a full narrative of the cruise (Baltimore, Wil- 

 liams and WiUcins Company, 1932; xiii + 331 pages with 

 198 illustrations). 



The preparations for, and the realization of, the pro- 

 gram would have been impossible without the generous 

 cooperation, expert advice, and contributions of special 



equipment and books received on all sides from inter- 

 ested organizations and investigators both in America 

 and in Europe. Among these, the Carnegie Institution of 

 Washington is indebted to the following: the United States 

 Navy Department, including particularly its Hydrographic 

 Office and Naval Research Laboratory; the Signal Corps 

 and the Air Corps of the War Department; the National 

 Museum, the Bureau of Fisheries, the Weather Bureau, 

 the Coast Guard, and the Coast and Geodetic Survey; the 

 Scripps Institution of Oceanography of the University of 

 California; the Museum of Comparative Zoology of Har- 

 vard University; the School of Geography of Clark Uni- 

 versity; the American Radio Relay League; the Geophys- 

 ical Institute, Bergen, Norway; the Marine Biological 

 Association of the United Kingdom, Plymouth, England; 

 the German Atlantic Expedition of the Meteor . Institut 

 fiir Meereskunde, Berlin, Germany; the British Admiral- 

 ty, London, England; the Carlsberg Laboratorium, Bu- 

 reau International pour I'Exploration de la Mer, and 

 LaboratoireHydrographique, Copenhagen, Denmark; and 

 many others. Dr. H. U. Sverdrup, now Director of the 

 Scripps Institution of Oceanography of the University of 

 California, at La Jolla, California, who was then a Re- 

 search Associate of the Carnegie Institution of Washing- 

 ton at the Geophysical Institute at Bergen, Norway, was 

 consulting oceanographer and physicist. 



In summarizing an enterprise such as the magnetic, 

 electric, and oceanographic surveys of the Carnegie and 

 of her predecessor the Galilee , which covered a quar- 

 ter of a century, and which required cooperative effort 

 and unselfish interest on the part of many skilled scien- 

 tists, it is impossible to allocate full and appropriate 

 credit. Captain W. J. Peters laid the broad foundation of 

 the work during the early cruises of both vessels, and 

 Captain J. P. Ault, who had had the good fortune to serve 

 under him, continued and developed that which Captain 

 Peters had so well begun. The original plan of the work 

 was envisioned by L. A. Bauer, the first Director of the 

 Department of Terrestrial Magnetism, Carnegie Institu- 

 tion of Washington; the development of suitable methods 

 and apparatus was the result of the painstaking effortsof 

 his co-workers at Washington. Truly, as was stated by 

 Captain Ault in an address during the commemorative 

 exercises held on board the Carnegie in San Francisco, 

 August 26, 1929, "The story of individual endeavor and 

 enterprise, of invention and accomplishment, cannot be 

 told." 



The present volume is concerned with investigations 

 during cruise VH on the electrical conditions of the low- 

 er atmosphere. In the introduction, O. H. Gish, Assist- 

 ant Director of the Department of Terrestrial Magnetism, 

 discusses the importance of studying these conditions 

 over the oceans. 



On previous cruises all the atmospheric-electric 

 observations were made with eye -reading instruments. 

 On cruise VII recording instruments were used for the 

 first time for continuous measurements of the potential- 

 gradient and the positive and negative conductivities. 

 Eye -reading observations of the concentration of con- 

 densation nuclei, the concentration of small ions, the 

 production of ions by penetrating radiations, and radio- 

 active content of the air were also made daily. One 

 section of the volume describes instruments and obser- 

 vational procedures. 



Various conditions of weather, sea, and vessel must 



