3IO ROCHESTER ACADEMY OF SCIENCE. [May 28, 



If the center of the cyclone passes over the observer the wind 

 directions will be as follows : 



With eastward progression of the storm the winds will be south- 

 east to south to the calm of the storm center and then north, with a 

 slight shifting to northwest on account of the vortical character of the 

 great whirl, as indicated in the diagram. 



With northward progression the wind will be northeast to east 

 and will change to the opposite direction. 



With northeast progression the winds will begin and continue 

 southeasterly until the center passes, when the winds shift suddenly to 

 the opposite quarter. 



In cases when the center of the cyclone center passes to the south 

 of the observer and he is located on the line of progression a-b the 

 wind slowly shifts from southeast through east, northeast to north. 

 That is the cloud motion ; but the weather-vane first points to the 

 southeast and veers about with the head eastward and northward. On 

 the other hand, if the cyclonic center passes to the north, or the 

 observer, for example, is situated along the line c-d, the wind shifts 

 in the direction opposite to the former case, and the weather-vane 

 points through south and southwest directions. 



By noting both wind directions and changes in the barometric 

 pressure the observer has quite definite knowledge of the cyclone's 

 progress. And if to the personal observations there can be added the 

 information given on the day's weather map, the knowledge of the 

 storm is sufficient to base a prediction with some assurance on the 

 immediate movement and behavior of the whirl. 



The region of lake Ontario and the St. Lawrence lies in the path 

 of more cyclones, probably, than any other district in the world. The 

 winter whirls which cross the continent, following in general the par- 

 allels of latitude, pass over the great lakes and move off down the St. 

 Lawrence to the north Adantic, where they usually die out, but some- 

 times push on to Europe. (Figure 2). 



There are other less frequented paths in the United States, one 

 from the Texas and lower Mississippi region, one from the gulf district 

 and one along the Atlantic coastline, which is followed by the West 

 Indian storms. The map, figure 2, shows how these three paths con- 

 verge in our region. 



Since the beginning of this year (1901) the cyclones have, been 

 behaving in an unusual manner. Instead of rapidly moving off the 



