OF PERIODIC PHENOMENA. 335 



grounds upon which it rests its claims to our 

 consideration. It is obvious that to insure suc- 

 cess in many field operations, as for instance the 

 raising of crops, the farmer must avail himself of 

 a particular period of year, most favourable, in 

 respect of the state of the atmosphere and soil, 

 for sowing the seed. Now, the determination of 

 this period might probably be made to rest more 

 safely on the first occurrence of some phenomenon 

 in the vegetable world, such as the leafing of some 

 tree or the flowering of some plant, than on the 

 return of a fixed day, even if the weather just at 

 that time were to be such as might be deemed 

 favourable for the undertaking in question. Thus, 

 the middle of March may be, in the long run, 

 the most suitable time for sowing several kinds 

 of grain ; but we know that in some years every- 

 thing at that time is locked up in frost and snow ; 

 and even jf it were not so, and the weather were 

 fine and open at the usual period of putting the 

 seed into the ground, still its germination, and the 

 casualties to which the young shoot is liable to be 

 exposed after it is evolved, must depend in a great 

 measure upon the actual condition of the soil in 

 respect of temperature and moisture ; which last 

 must depend upon the whole character of the 

 previous weather from the very commencement of 

 the year. Whatever be the weather just when 

 the farmer sows, it must make a wide difference 

 whether the quantity of rain for several weeks 

 previous has been in excess or not, or whether 

 the mean temperature of the soil has reached a 



