METEOROLOGY. 



503 



ably Woeikoff or Wesseloffski), to which we add the hourly distribution 

 of 162 tornadoes in the United States as given by Finley (also quoted 

 by Buchan, without mention of source) : 



Hour ending — 



1 a. m 



2 a. m 



3 a. m 



1 a. m 



5 a. m 



6 a.m 



7 a. m 



8 a. m 



9 a. ni 



10 a. in 



11 a.m 



Noon 



1 p.m 



2 p. m 



3 p.m 



4 p. m 



5 p. m 



6 p. m 



7 p. m 



8 p. m 



9 p. m 



10 p. m 



11 p.m 



12 miduight 



Sums. 



Frequency of thunder-Btorme at Ekaterine- 

 burg, 1859-1872. 



April. 



27 



May. 



2 

 4 

 8 

 10 

 6 

 5 

 6 

 7 

 5 

 6 

 3 

 1 

 1 



64 



June. 



5 

 1 



1 



1 



2 



3 



2 



5 



4 



6 



8 



14 



19 



21 



22 



26 



24 



25 



15 



16 



14 



8 



6 



7 



July. 



5 

 5 

 4 

 2 

 1 

 3 

 3 

 2 

 4 

 7 



12 

 30 

 25 

 29 

 35 

 45 

 33 

 30 

 20 

 20 

 14 

 10 

 6 

 6 



255 | 351 



Aug. 



2 



1 



5 



4 



5 



5 



12 



15 



20 



9 



11 



10 



9 



6 



5 



5 



8 



144 



Sept. Year. 



15 



15 



8 



6 



6 



4 



6 



5 



10 



10 



19 



25 



53 



60 



74 



89 



101 



73 



75 



54 



52 



42 



29 



18 



22 



856 



<*H CD 

 ."S 





Year. 



5 

 3 



4 

 1 



7 

 13 



• 47 

 52 

 17 



7 

 4 



162 



g « 



Six 

 years. 







1 



2 



1 



3 



20 



15 



13 



3 



1 











59 



From these and other considerations Buchan concludes: "Given an 

 initial difference of electric potential, it is easy to understand how the 

 most violent thunder-storms are produced." 



"The formation of the electrical manifestations of the thunder-storms 

 and tornadoes requires aqueous vapor and that there shall be masses of 

 descending cold air along with the ascending current of warm moist air; 

 thus at Mauritius there are no thunder-storms so long as during June, 

 July, August, and September the island remains in the heart of the 

 southeast trades where the conditions of descending cold currents of 

 any considerable volume are not present." In our present almost utter 

 ignorance of the actual electric potential of the air and vapor as dis. 



