404 



The Ohio Naturalist. 



[Vol. Ill, No. 6, 



the prevailing direction has l)een south-east, so that there is no 

 very decisive evidence in favor of anj' particular direction. 

 Cleveland shows a prevailing south-east wind, but Pittsburg is 

 decidedly a station of north-west winds. 



For most of the stations the windiest month of the 3'ear is 

 March, and the calmest month August, although Cleveland's 

 highest winds are in November. In the course of the year there 

 are some interesting variations in wind direction at some of the 

 stations, as the table below will show. At the three lake stations 

 the wind seems to show during the earlier part of the 3'ear a ten- 

 dency to veer to a more westerly direction than is taken during 

 the later months. 



WIND, DIRECTION AND VELOCITY. 



Stations. 



Cincinnati . 



Cohimbus . . 

 Cleveland . 



Toledo 



Pittsburg. . . 

 Sanduskj- . . 



f Prevailing direction, 

 I Miles per hour 



( Prevailing direction, 

 I Miles per hour 



( Prevailing direction, 

 \ Miles per hour 



( Prevailing direction, 

 \ Miles per hour. . 



( Prevailing direction, 

 ( Miles per hour. . 



( Prevailing direction, 

 '( Miles per hour. . 



CO , 

 1/ v 



§5 



s e 

 7 5 



s w 



8.1 



s e 

 13-7 



s w 

 10. o 



n w 



6.S 



s w 



8.6 



KILLING FROST, — DATE OF FIRST AND LAST. 



The date of the last killing frost in the spring and the first one 

 in the fall, is perhaps to be ranked as one of the most determina- 

 tive factors in ecology, since upon it depends in a measure the 

 length of the growing season. 



The data used in this compilation cover a period of ten years 

 for most of the stations, although many of these have only partial 

 records for the earlier ^-ears. Records from twenty-eight stations 

 throughout the State were used, but the results are so conflicting 

 that only a few general conclusions can now be stated. 



In a general way the immediate Ohio valley shows a longer 

 growing season than the central part of the State, but about the 

 same length of season as the region immediately adjoining the 

 lake. Sandusk}', with a growing season of 201 days, and Mari- 

 etta, with 186 days, stand at one extreme, while Hillhouse (Lake 

 county), with 131 days, and Bowling Green and Defiance, each 

 with 141 days, stand at the other extreme. 



