TROGRESS OF METEOROLOGY IN 1889. 245 



tlie conditions which prevail in nature, since, in that case, the rotation 

 is doubtless kept up b}' the upward movement along the axis and the 

 consequent aspiration of the surrounding air into the area of gyration, 

 but in general tlie analogy seems quite complete. [Nature, xxxviii, 

 p 104.) 



Mr. Ealph Abercromby has made special observations on the upper 

 wind currents over the equator in the Atlantic Ocean. In December 

 (1888) the northeast and southeast trades both turned into a common, 

 light-surface, easterly current along the line of the doldrums ; low clouds 

 from southeast drove over the nortlieast trade up to 15^ north, and from 

 300 miles south of the equator, a very high current from northwest pre- 

 vailed over the southeast trade. From the equator southward 300 miles, 

 no high observations were obtained. In May a somewhat different 

 system prevailed. The northeast trade turned to north as it approached 

 the doldrums, instead of towards the east, as in December. In the calm 

 belt, it met a light, easterly current without producing much rain; 

 while further south the regular southeast trade was experienced as lar 

 south as 8'^ south, when the northeast monsoon prevailed along the 

 Brazilian coast nearly down to Rio Janeiro. JSo southeast wind could 

 be discovered at any level over the northeast trade. 



These observations are held to confirm in a striking manner his pre- 

 vious discovery "that the highest air current over the equatorial dol- 

 drums is from the eastward, lying between the southwest current which 

 flows on one side over the northeast trade, and the northwest current 

 which flows on the other side over the southeast trade.-' 



With respect to the general circulation of the atmosphere we know 

 that the surface trades either die out at the doldrums or unite into one 

 moderate east current; that the low and middle currents over the dol- 

 drums are very variable, but that tlie winds at these low aiul middle 

 levels, 2,000 to 20,000 feet, come usually from the southeast over the 

 northeast trade, and from the northeast over the southeast trade, and 

 tliat the highest currents — over 20,000 feet — move from east over tlie 

 doldrums, from southwest over the northeast trade, and from northwest 

 over the southeast trade. 



What we do not know is the relation of the southeast low and middle 

 current over the northeast trade to the southeast trade on the other 

 side of the equator, nor do we yet know what becomes of this middle 

 current in the northern hemisphere. 



The simple scheme which assumes nothing but an upward current over 

 the doldrums, and a return current toward each pole is not continued by 

 observations. There is always a regular vertical succession of the upper 

 currents as we ascend according to the hemisphere. {Nature, XL, p. 207.) 



Thcrmo-dynamics of the atmosphere. — Dr. W. von Bezold has continued 

 his contribution upon the thermo dynamics of the atmosphere in the 

 Sitsungsberichte of the Berlin Academy. The whole series of papers 

 are being prepared by Professor Abbe lor publication in this lieport. 



