METEOROLOGY AND ALLIED SUBJECTS. 



303 



5° latitude and 10° longitude. [In tlie statistical atlas published by the 

 Unites States Census Ofiflce in 1876 may be found a similar chart for 

 each one degree square for the United States.] 



Van Bebber finds, however, that the irregularities in contiguous 

 years are such as to show that five years is by far not enough to estab- 

 lish the normal distribution of storm-centers. 



The following table shows the annual means for each zone, corrected 

 so as to reduce to a uniform area with the zone of 50° latitude : 



In reference to the paths pursued by the minima, Van Bebber finds 

 the routes most frequented to be as follows : 



(A) Passing through Northwestern Ireland; then along the coast of 

 Norway into the Arctic Circle; thence dividing and passing on either (1) 

 northward until swallowed up in the ocean, or (2) to the White Sea, or 

 (3) southeast to the interior of Eussia. 



(B) Passing near Great Britain ; thence either directly over the North 

 Sea, Southern Scandinavia, central and southern Baltic Sea to Finland 

 and the Baltic provinces of Eussia. 



(C) Passing southwest of Great Britain, southeastward over France 

 to the Mediterranean. 



In general, the minima seem to prefer the coast; mountains do not 

 apparently attract them. (Z. 0. G. M., XVI, 1881, p. 418.) 



Einiker has studied the mass of data collected by the forestry com- 

 mission of Aargau, Switzerland, relative to the occurrence of hail. He 

 finds an intimate connection between the frequency and severity of hail 

 storms and the distribution of forests, cleared land, &c. ; the more forests, 

 so much the less hail. {Z. 0. G. M., XVI, 1881, p. 525.) 



Lancaster, of Brussels, has discussed the observations of thunder 

 storms in Belgium during 1878. He finds the trend of the paths of the 

 43 storms distributed as follows: Toward the SW., 25; S., 8; SE., 4; 

 W., 4; NW., 1 ; NE., 1. The hourly velocity of progress averages 5 kil. 



On the average of 45 years, 1833 to 1878, the annual distribution of 

 days with thunder is as follows : 



Nnmber of storms. 



January 12 



February 10 



March 27 



April 45 



May 108 



June 143 



Number of storms. 



July 158 



August. 159 



September 68 



October 21 



November 6 



December 4 



