PREFACE 



be considered in any analysis of observed atmospheric- 

 electric data. Because of the importance in interpreting 

 measurements, detailed notes were kept of weather con- 

 ditions, including nearby clouds, variations in wind 

 direction and velocity, changing conditions of mist or 

 haze, and other related meteorological factors. One 

 section gives an abstract of these notes, as entered in 

 the ship's log by the sailing officers and of the notes on 

 engine operation. Positions of the mainsail were re- 

 corded by the observer in charge of the atmospheric- 

 electric work. 



W. C. Parkinson, senior scientific officer, was in 

 charge of the atmospheric-electric program throughout 

 cruise VU. O. W. Torreson, executive officer, assisted 

 in the observations and computations from May 1928 

 through July 1929 and S. E. Forbush, who replaced him, 

 for the remainder of the cruise. 



Reports of the work done during each leg of the 

 cruise were mailed at every port of call. These were 

 examined at Washington and comments submitted prompt- 

 ly to the observers on board. These reports and the sug- 

 gestions are included here because of potential value in 

 future operations at sea. 



A systematized program of observation was followed 

 insofar as possible. Over two hundred and fifty complete 

 daily observations were made for each of the elements 

 included in the program. Diurnal-variation series of 

 twenty-four consequtive hourly sets of observations were 

 scheduled to be made at weekly intervals and thirty-two 

 complete or partial series were obtained. Several of the 

 series could not be completed because instrumental dif- 

 ficulties developed or unfavorable weather conditions 

 made observing impossible. Compilations of the daily 

 observations, diurnal-variation series, and the automat- 

 ically recorded data are given in four tables in sections 

 V to Vni. The final section (DC) comprises eight short 

 discussions of studies of the great number of observa- 

 tional data. 



O. W. Torreson edited and compiled the material 

 for publication. This volume is the twelfth of the series 

 "Scientific results of cruise VII of the Carnegie during 

 1928-1929 under command of Captain J. P. Ault." It is 

 the third of the Oceanographical Reports. 



J. A. Fleming 

 Director, Department of Terrestrial Magnetism 



