

THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Art. XXVII. — Contributions to Meteorology; by Elias 

 Loomis, Professor of Natural Philosophy in Yale University. 

 Twenty-third paper. 



[Read before the National Academy of Sciences, Nov. 14, 1888.] 



Relation of rain-areas to areas of high and loic pressure. 



1. In former papers (Nos. 6, 7, 12, 17 and 18) I have in- 

 vestigated the circumstances attending remarkable rain-falls 

 both in the United States and Europe, and obtained some im- 

 portant results. Since the publication of those papers, the 

 materials suited to this incjuiry have greatly increased, and I 

 have revised the investigation, availing myself of all the ma- 

 terials within my reach. The published volumes of Signal 

 Service tri-daily observations embrace a period of 41 months, 

 whereas when I prepared papers 6 and 7, only 15 months' ob- 

 servations had been published. The observations of 41 months 

 show 106 cases in which there was a rain-fall of at least two 

 inches in eight hours, at some station east of the Rocky Moun- 

 tains, and North of the parallel of 36 degrees. These cases 

 were distributed by seasons as follows : Winter, 7 ; Spring, 14 ; 

 Summer, 53 ; and Autumn, 32 ; which shows that great rains 

 occur most frequently during that period of the year in which 

 the atmosphere contains the greatest amount of vapor. 



Great rain-falls occur much more frequently near the Atlantic 

 coast, than they do at interior stations. Of the 106 cases com- 

 pared, 60 occurred on or near the Atlantic coast, and 46 at the 

 interior stations. As there were numerous changes in the 



Am. Jour. Sci.— Third Series, Vol. XXXYII, No. 220. — April, 1889. 

 16 



