November 24, 1916] 



SCIENCE 



753 



Hazen, A. W. Greely, followed by Professors 

 H. W. Harrington, Willis Moore and Charles 

 F. Marvin. The theoretical evolution has 

 been principally accomplished by a civilian 

 staff, among whom may be mentioned Ferrel, 

 Abbe, Maury and Humphreys, and the prac- 

 tical work by officers of the army, by observers 

 and professors. The present force has risen 

 from the lower grades through successful work 

 of a quarter of a century or more to command- 

 ing positions. 



This review does not discuss the relative 

 merits of the various systems, official and non- 

 official, but seeks to summarize with brief com- 

 ments the accuracy or fulness of the official 

 national methods herein presented, concerning 

 which the public is not generally informed. 



The reviewer prefaces his comments by 

 stating that notwithstanding his open mind to 

 scientific discoveries in meteorology, yet his 

 views on long-time forecasts were formulated 

 and published more than a quarter of a cen- 

 tury since, in American Weather, N". T., 1888. 

 In this publication, the first American work 

 wherein definite rules for forecasting were 

 advanced, after quoting Blanford as to 

 droughts and temperatures, the present writer 

 found the sun-spot theory fallacious as to 

 rainfall in the United States, but added: 



The advances of meteorology are insufficient to 

 justify predictions of the weather for a season in 

 advance. There are apparently good grounds for 

 believing that general laws can be deduced by 

 which, from abnormal distributions of atmospheric 

 pressure, to predict for prolonged periods in ad- 

 vance the general character of the coming season, 

 as warm or cold, and wet or dry. 



Almost without exception the authors of 

 the various memoirs in weather forecasting 

 have had practical experience in meteorolog- 

 ical work with the Weather Bureau for thirty 

 years, and so speak with a degree of authority 

 that makes their opinions worthy of careful 

 consideration. 



The first essay, modestly styled Introduc- 

 tory Note, by Professor C. F. Marvin, sets forth 

 clearly and succinctly the theory of atmos- 

 pheric circulation, the essential basis of the 



science of forecasting. His action in promptly 

 initiating these investigations, in 1913, gives 

 promise of further memoirs as later studies 

 add to meteorological knowledge. 



Professor W. J. Humphreys has brought to- 

 gether a comprehensive summary of existing 

 knowledge as to winds, cyclones and anti- 

 cyclones. He advances reasons as to why the 

 average velocity of winds steadily increases to 

 600 meters' elevation, decreases to 1,000 meters, 

 and after fluctuations steadily increases from 

 2,000 meters upward. In this connection he 

 believes that: 



The horizontal pressure gradient maintained by 

 the temperature difference between adjacent re- 

 gions is approximately constant with a tendency 

 towards a maximum gradient at about 8 kilo- 

 meters roughly. 



In connection with the origin of cyclones 

 and anti-cyclones Humphreys considers the 

 various hypotheses: Ferrel's convectional, 

 Hann's driven-eddy— both discussed by Pro- 

 fessor Davis — and Mitham's counter-current. 

 He believes that none of these theories con- 

 tains clear and workable conceptions of "the 

 origin, mechanism or maintenance of the 

 extra-tropical cyclones," but that they " still 

 remain the meteorological mysteries they have 

 always been." He points out that tornadoes, 

 "well-nigh peculiar to the United States east 

 of the Eocky Mountains," develop usually in 

 the southeast quadrant of a low-pressure area, 

 the tornado being " a vigorous convection be- 

 tween strong neighboring counter-currents." 

 He indicates the presence of permanent and 

 semi-permanent low areas. 



It is to be regretted that he did not con- 

 sider in this connection the normal transfer to 

 and from various regions, in the northern 

 hemisphere of pressures from month to month, 

 which, deduced largely from the international 

 series of simultaneous observations, were 

 charted and briefly described by the writer 

 twenty-six years ago. 



Coming to the practical problems, Professor 

 A. H. Henry treats the subject under the head 

 of weather forecasting, pressure changes, 

 highs and lows, and forecasts in the Washing- 



