INDUSTRIAL PROGRESS DURING THE YEAR 1875. xxxix 



rainfall has been published by Hann, who has shown that 

 we have no reason to believe that the condensation of atmos- 

 pheric vapor directly causes large observable changes of 

 pressure. In order, then, to understand why so great de- 

 pressions of the barometer are observed in the midst of ev- 

 ery storm, he finds it necessary to adopt the mechanical prin- 

 ciples which have been developed so fully by Ferrel and oth- 

 ers, and which have been adopted by some of the American 

 meteorologists for many years. 



In the application of the barometer to hypsometric pur- 

 poses, we notice the empirical tables prepared by Professor 

 Whitney and Mr. Pettee especially for the climate of Cali- 

 fornia, which give corrections to be applied to the results of 

 computation by the ordinary formulae, in order to obtain 

 more correct altitudes. 



Winds. The report of the permanent committee appoint- 

 ed at the Meteorological Congress at Vienna has recently 

 been received, in which is given the proceedings of the meet- 

 ings held by the committee, and in the appendix the papers 

 communicated to it by the meteorologists of Europe. Among 

 these, the greatest interest will attach to the short prelimi- 

 nary reports by Buys Ballot, of Holland, Wild, of Russia, 

 and Scott, of England, on the relation between the velocity 

 and the force of the wind. An investigation of the same 

 subject has also just been published by Hagen, of Berlin ; 

 and from his own, as well as the other papers referred to, it 

 seems certain that the friction of the air blowing past the edge 

 of a plain circular disk brings about an increase in the press- 

 ure experienced by that disk. So that the pressure is not, 

 as ordinarily assumed, proportional to the area of the disk 

 and the square of the velocity of the wind, but may be said 

 to depend upon the circumference of the disk, and upon oth- 

 er powers of the velocity. A fuller investigation of this sub- 

 ject will be necessary before we can at all understand the 

 effects produced by the power of the winds of tornadoes and 

 hurricanes. The complete memoir by Dohrandt and Wild, 

 of St. Petersburg, will be found in Wild's " Repertorium." 



An important memoir by Blandford has been published 

 under the title of the " Winds of Northern India," which, 

 however, contains much more than the title would seem to 

 indicate. 



