174: ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



In order to improve on these charts, lie proposes to extend 

 his daily weather-charts by extra- and interpolation over 

 those portions of the ocean from which he lias no direct ob- 

 servations, and to combine into monthly means the readings 

 taken from his daily charts. At present he has charts for 

 only two years IS 74 and 1875 which he gives, and which, 

 of course, show a distribution of pressure decidedly different 

 from that given in his general chart. The charts are also 

 given for December, 1874, and February, 1875 ; that for De- 

 cember showing a very remarkable departure from what 

 would be considered a normal distribution. 



He seems to consider that three minima namelv, that of 

 Davis Strait, that northeast of Iceland, and that southwest 

 of Iceland by varying their position and relative develop- 

 ment, alternate in their control over the winds and weather 

 of the Atlantic. 



The character of the weather which prevails over North- 

 ern Europe depends, therefore, entirely upon the predomi- 

 nance of one or other of the barometric minima of the North 

 Atlantic Ocean. While recognizing the fact that, theoreti- 

 cally, the wind affects the distribution of pressure, he seems 

 to only partially appreciate the importance of the law estab- 

 lished by theoretical mechanics namely, that it is not so 

 much the barometric pressure that determines the wind, as it 

 is the wind that determines the pressure. 



lie recognizes the fact that the area studied by him is but 

 a very small portion of the northern hemisphere, and that 

 the causes of the important variations in the distribution of 

 pressure must be, at least in part, looked for outside of the 

 region covered by his maps. In this respect, certainly, the 

 monthly maps published by Ferrel in 1877, and the daily 

 weather-maps of the northern hemisphere published by the 

 Signal-Office in 1878, must be recognized as the first steps 

 in the proper treatment of this subject. 



EVAPORATION AND PRECIPITATION. 



"Weilenmann, in the Schweizerischen Met. J3eob., 1877, vol. 

 xii., gives the development of a formula for the quantity of 

 evaporation, which agrees, in the most remarkable manner, 

 with observations at Vienna, St. Petersburg, Mont Souris, 

 1*01:1, and Tiflis. This memoir and his essay on Atmospheric 



