PREFACE 



an area in the trade-wind belt may be expected to give a 

 close approximation of the average upper -wind condi- 

 tions prevailing at that season. Thus 171 flights, al- 

 though not sufficient for the purposes of the study of up- 

 per winds over a continental region, may be sufficient to 

 extend considerably our knowledge of the trade-wind cir- 

 culation over the Pacific. 



Although the surface-wind observations for the Pa- 

 cific Ocean had been collected for many years, almost 

 nothing had been learned of the upper winds over the 

 same region. The Carnegie observations discussed in 

 this memoir represent a considerable contribution to 

 meteorology which will find use both in the theoretical 

 study of the circulation of the atmosphere and in plan- 

 ning air routes across the Pacific. 



The present volume is the fifth in the series of "Sci- 

 entific results of cruise VII of the Carnegie during 1928- 

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

 second of the Meteorological Reports. The first of these, 



"Meteorological results of cruise VII of the Carnegie. 

 1928-1929" by Woodrow C. Jacobs and Katherine B. 

 Clarke (1943), contains the data resulting from the ob- 

 servations and records of atmospheric pressure, air 

 temperature, sea-surface temperature, humidity, evap- 

 oration, and miscellaneous meteorological phenomena. 

 Mr. Thomson's discussion provides a fairly com- 

 plete account of the technique employed in making pilot- 

 balloon observations on shipboard. Besides giving the 

 results of the flights themselves, the weather conditions 

 prevailing at the time of the flights are described in de- 

 tail. The observations are quite fully represented in 

 charts and tables so that it is hoped the data can be uti- 

 lized for many different purposes by investigators with 

 a minimum of additional work. 



J. A. Fleming 

 Director, Department of Terrestrial Magnetism 



