570 



SCIENCE. 



[N. S. Vol. I. No. 21. 



FOEHN-LIKE EAST WINDS IN AFRICA. 



Danckelman, who for some years has 

 made a special study of African meteor- 

 ology, contributes a note on the foehn-like 

 east winds felt on the southwest coast of 

 Afi'ica, about the southern tropic (Met. 

 Zeitschr., Januarj'', 1895). In the interior, 

 temperatures above 27 °C are unknown in 

 the winter (April to October) ; but on the 

 coast in this season, maxima over 30°, and 

 even as high as 39°, are reported, east 

 winds and low humidity occurring at the 

 same time. As so high a temperature can- 

 not be ascribed to heat from the interior, 

 Danckelman explains it as the result of the 

 dynamic warming of the wind during its 

 descent from the interior highlands. This 

 is only one more illustration of the impor- 

 tance of adiabatic changes of temperature in 

 meteorological phenomena ; the Swiss foehn 

 and our western chinook, the extraordinary 

 foehn-like winds of west Greenland, the 

 ' hot winds ' of India and of Kansas, as 

 well as the ordinary warm or hot southerly 

 cyclonic winds, or 'siroccos,' all owing a 

 greater or less share of their high tempera- 

 tures to the heat developed by compression 

 during the descent of air from higher to 

 lower levels. 



THE AMERICAN METEOROLOGICAL JOURNAL. 



The American Meteorological Journal, 

 conducted for a number of years by Profes- 

 sor Harrington at Ann Arbor, and since 

 1892 edited by E. DeC. Ward and published 

 by Ginn & Co., Boston, is an able exponent 

 of the science of the atmosphere for this 

 country. The closing number (AprU, 1895) 

 of the eleventh volume opens with a note 

 by the editor, reviewing the recent work of 

 the journal, and making an excellent show- 

 ing for its continuation. Its original arti- 

 cles make it of value to the investigator ; 

 its notes and reviews place much important 

 material before the general student ; and 

 its more elementary or educational articles 



must ]3rove useful to the teacher, for in 

 spite of a recent assertion to the eii'ect that 

 the meteorological aspects of geograplij'^ are • 

 well taught in our schools, there is room 

 for much improvement in this direction. 

 The April number contains notes on signs 

 of a recent change of popular opinion con- 

 cerning the efl'ect of cultivation on rainfall 

 in Iowa, the proceedings of the last meeting 

 of the New England Meteorological So- 

 ciety — the only societj^ of the kind, we be- 

 lieve, in this country — and diagrams of a 

 curiously curved storm track from the Pilot 

 chart of the Hydrographic office ; reviews 

 of the Blue Hill (Mass.) observations for 



1893, of Ley's new work on clouds, and of a 

 new Danish series of monthly pressure 

 charts for the North Atlantic. The editor 

 contributes an account of Swiss studies of 

 thunderstorms, and a description of meteor- 

 ological work in India and Australia. The 

 wind known as the ' southerly burster,' 

 as felt at Sydney, has recently been studied 

 in a prize essay ; it recalls in many particu- 

 lars the ' northers ' of our Texan coast. 



NOTE ON CROLL'S GLACIAL THEORY. 



A BRIEF article by the undersigned (re- 

 printed in Amer. Met. Journal for April 

 from the Trans. Edinb. Geol. Soc, vii., 



1894, 77-80) suggests a common explana- 

 tion for three forms of geologically recent 

 climatic change, namely, the glaciation of 

 many northern lands, the expansion of 

 manj=' interior lakes, and the production of 

 wadies by water action in the now dry 

 Sahara. Accepting CroU's theory of the 

 coincidence of glacial conditions with long 

 aphelion winters during periods of gi-eat 

 orbital eccentricity, it is argued that the 

 chief cause of snowy precipitation at such 

 times must be the greater activity of cyclonic 

 processes, then intensified b}' the stronger 

 general circumpolar circulation, in turn ac- 

 celerated bj' the increased winter contrast 

 of polar and equatorial temperatures; 



