METEOROLOGY AND ALLIED SUBJECTS. 



299 



greater thau duriug cloudy days. The range for the former is, in the 

 summer season, twice that for the latter. For clear days the range of 

 wind force is remarkably great, while the gradient remains unchanged, 

 a condition that requires the introduction of an explanation in the 

 manner suggested by Koppen {Z. 0. G. If., XIV, pp. 333-34:9.) At sea 

 the diurnal range, as deduced for marine records, shows nothing of all 

 this remarkable increase of wind force at 2 p. m. Finally, Sprung com- 

 pares the anemometer records at 4 stations with the corresi^onding esti- 

 mates on the Beaufort scale, and deduces the following formula : 



Velocity in meters per second = 0.360 + 1.691 x Beaufort scale of force. 

 {Z. 0. G. Jf., XVI, 1881, p. 356.) 



The above work by Sprung has been followed by a similar study by 

 Eev. W. Clement Ley, who has discussed the observations at Stony- 

 hurst and Kew, and who concludes that if we could have isobars for the 

 level of the cirrus clouds, we would there find above the deepest cyclone 

 only a slight secondary depression circulating around a portion of the 

 great polar depression. He submits the question "Cannot the fact that 

 a given gradient for east winds obtains only in the lower atmosphere, 

 while a similar gradient for west winds holds good for the whole atmos- 

 phere, be brought into connection through known laws of mechanics with 

 the fact of the greater force of the east over the west winds at the earth's 

 surface?" [Z. 0. G. M., XVI, 1881, p. 535.) 



Supan, professor of geography in the University of Czernowitz, has 

 published a valuable work, entitled " Statistik der unteren Luftstro- 

 mungen," in which he has utilized the great collection of data published 

 in Coflin's '"Winds of the Globe" (Washington, 1876), and almost as 

 much more collated by himself. Supan has, in fact, endeavored to util- 

 ize only the longer series of observations, and he confines himself to 

 annual percentages of the frequency of the winds, omitting the calms, 

 which are not given with sufficient accuracy and uniformity by the vari- 

 ous observers. Only about thirty pages of the whole volume are occu- 

 pied with general analysis and conclusions. 



In elucidating the mutual relations of wind and pressure, Supan cal- 

 culates the pressure for January over the X. Atlantic Ocean at various 

 altitudes and degrees of latitude. Adopting observed pressures at sea- 

 level and Glaishers' rate of diminution of temj^erature with altitude, 

 Supan obtains the pressures in the following table: 



