E. Loomis — Areas of low pressure. 



15 



the United States. Moreover we find no correspondence be- 

 tween the average rate of progress of storm centers for the 

 different months of the year, and the average velocity of the 

 wind. The inequality in the values of the ratio for the differ- 

 ent months of the year is quite noticeable, but this may be 

 partly due to the small number of the observations. 



I next endeavored to determine the mean velocity of the 

 wind in the neighborhood of the West India Islands, but 

 found observations for only seven stations south of lat. 27°. 

 The following table shows the results for August, September 

 and October, which are the only months for which there is an ob- 

 servation of more than one cyclone, with the exception of June, 

 for which month there are three observations. 



August 



September. 

 October 



Velocity. 



Wind. 



5-79 

 5-98 

 6-70 



Storms. 



14-44 

 14-00 

 1281 



2-5 

 2-3 

 1-9 



I next determined the mean velocity of the wind for that 

 part of the Atlantic Ocean in the neighborhood of the usual 

 tracks of storm centers, and have adopted the results contained 

 in No. 3 of the Mittheilungen aus der ISTorddeutsche Seewarte. 

 The first line of the following table presents a summary of 

 these results for the four seasons of the year, the force of the 

 wind being estimated in units of Beaufort's scale (1-12). 





Winter. 



Spring. 



Summer. 



Autumn. 



Beaufort's numbers 



Miles per hour 



Storms . 



Ratio . 



5-9 

 33-0 

 18-4 



05 



5-5 

 30-8 

 18-6 



0-6 



4-5 

 25-5 

 16-5 



0-6 



5-3 

 29-7 

 18-6 



0-6 



The second line shows the velocities denoted by Beaufort's 

 numbers, reduced to miles per hour according to the table pre- 

 pared by the British Meteorological committee ; the third line 

 shows the average rate of progress of storms, and the fourth 

 line shows the ratio of the numbers in the two preceding lines. 



If we group together the results now obtained, we shall have 

 the following summary for the average rate of progress of 

 storm centers, the average velocity of the winds, and the ratio 

 of these two velocities : 





Storms. 



Winds. 



Eatio. 



United States 



28-4 

 18-0 

 16-7 

 13-7 



8-4 



9-5 



29-8 



10-3 



6-2 



6-5 



3-0 



North Atlantic Ocean 



6 



Europe . .. .._ 



West Indies . 



Southern Asia 



1-6 

 22 

 1-3 



