Dw 



PREFACE 



This collection of data is published in response to the need expressed 

 by the following resolution passed by the International Meteorological 

 Conference in session at Utrecht in September 1923: 



RESOLUTION 



13- (4) V. Considering Professor Exner's proposal about the calculation 

 of the correlations between weather-anomalies in regions far from each other, 

 the Conference thinks that publication of long and homogeneous series of 

 observations in the form of monthly means of pressure, temperature, and rainfall 

 would be of the highest importance for the study of the general circulation of 

 the atmosphere. This publication should comprise a small number of stations 

 at a mutual distance of 500 to 1000 kilometers, preferably belonging to the 

 Reseau Mondial, and if these should fail, other stations with a longer homo- 

 geneous series. It proposes that the various meteorological institutes should 

 establish such series up to the year 1920 and invites the following gentlemen 

 to see to the execution of this Resolution. 



Dr. Walker for the stations of Asia ; 



Prof. Exner for the stations of Europe ; 



Mr. Clayton for the stations of America ; 



Dr. Simpson for the stations of Africa, Australia and the oceans. 



The data for 1921 to 1930 for the British Empire, for Africa, for 

 Australia, and for the island stations in the ocean were gathered by 

 Dr. G. C. Simpson or under his direction. 



Owing to Dr. Exner's death since the last publication, Miss 

 Frances L. Clayton undertook the collection of data from Europe. 

 vShe also carried on most of the correspondence necessary for gather- 

 ing data from other parts of the world. 



Mr. R. C. Mossman is largely responsible, as in the case of the 

 preceding publication, for the data gathered from South America. 



The collectors of the data are grateful for the hearty cooperation 

 of the various weather services in compiling and forwarding the 

 data requested. 



Meteorology stands deeply indebted to Mr. John A. Roebling for 

 providing the means to publish this long-desired collection of funda- 

 mental data, which cannot but be of great use in future theoretical 

 and practical researches. 



