CONTRIBUTFONS TO METEOROLOGY. 



57 



(^oluiim 2 sliow.s tlio vi'ldclty of inovtMiuMit for v.ivh inoiitli, expn'ssed in myriiimoters for 

 tweiityfonr iioiirs ; coluimi .'J sliows the veUndty tvKl)ressi'(l in English miles [wv hour; coliiinii -4 

 sbows the velocity of moveinent of .storm centers for tlic United States, and column 5 shows the 

 ratio of the iinmliers in columns 3 niul 4. 



We see that in tlie United States the average velocity of movement for the entire year is 

 abont two-thirds greater tiian it is in Enrojje. This ratio is greatest in winter, when it amounts 

 to 1.9, and least in the autumn, when it amounts to 1.5. So large a ditt'erence between the mean 

 ratio of progress of storm centers in the United States and Europe must he the result of a 

 permanent cause of great energy. A conii>arison of the cases of most rapid movement in 

 Europe with the cases of extremely slow movement may afford some clue to the nature of 

 this cause. 



S4. The most satisfactory materials I have found u|)on which to base such a comparison are 

 the daily weather charts, publislied by the Danish Government for three years, from December, 

 1873, to November, 1876, and by the Danish Governmenr in connection with the Deutsche See- 

 warte, from December, 1880, to August, 1881. Table XXXIV contains the most decided cases of 

 rapid motion that 1 have been able to tind from a comparison of these charts. They are cases in 

 which the depression of the barometer was considerable, and generally there was no second low 

 center in the vicinity. The charts show a great number of other cases in which the movement of 

 low centers apparently was equally rapid ; but in some of them the exact position of the low 



Table XXXIV. — Atlantic and European storms advancing at least 750 miles in twenty-four hours. 



S. Mis. 154- 



