CYCLONIC STORMS IN TEMPERATURE LATITUDES 499 



the amount of rainfall, since that is largely influenced by latitude, near- 

 ness to the ocean, the location of mountains, and other topographic con- 

 siderations. When a given area is compared with itself at different 

 periods, however, the number of storms is roughly proportioned to the 

 rainfall up to certain limits, for the topographic conditions in any one 

 place, of course, remain constant. 



The data for storms in Europe are much less reliable than in America. 

 The only available series of charts is that of the ^^Deutsche Seewarte," 

 where, as has already been stated, the 16 years from 1876 to 1891 are 

 included. Unfortunately, the maps for the different years are not homo- 

 geneous. The area which they cover varies. Moreover, in the later years 

 the diata not only cover a wider area than at the beginning, but barometric 

 minima of smaller dimensions have apparently been included. The rea- 

 son for thinking this is that if we take the area included in the first year 

 and compare it with the same area in later years we find that the number 

 of storms apparently increases enormously. This is illustrated in the 

 following table : 



Table 3 



Storminess for Periods of 4 Years in Europe and America in per cent of 

 Averages for 16 and 30 Years respectively 



Years Europe America 



Per cent Per cent 



187&-1879 67.5 89.5 



1880-1883 103.0 79.0 



1884-1887 104.3 90.0 



1888-1891 123.8 99.9 



1892-1895 ■ 110.1 



189&-1899 103.0 



1900-1903 100.5 



1904-1907 105.7 



1908-1911 98.6 



Here the 16 years have been divided into four groups, each containing 

 four years. The average number of storms for the 16 years in the area 

 covered by the first map is called 100 per cent. The figures show tlie 

 number for each successive series of years. It will be seen that in the 

 last group the number is almost twice as great as in the first. In America 

 the figures are much more homogeneous, as appears in the same table, 

 although here, too, the earlier years show a deficiency which is probably 

 due to scarcity of observations. In the American figures for the first two 

 groups of years allowance has been made for the fact that the data only 

 extend as far west as the 100th meridian, while in later years the whole 



