INFLUENCE OF THE SEASONS. 131 



of the soil and the atmosphere. Grass will not vegetate when 

 the tempcratnro of the air is higher than GG° unless the soil is 

 very moist. When the vapor of the air is at its maximum, or 

 when the air is saturated with moisture, vegetation advances 

 with the greatest rapidity, and this most frequently happens 

 with us in the earlier growing months, April, May and June. 

 But when the moisture in the atmosphere is slight, and the soil 

 becomes dry, and the subsoil is porous, the turf of our fields 

 and pastures sufters from the drought, and scarcely a year 

 passes over us when this does not happen. 



A writer in the Journal of the Royal Agricultural Society, 

 (quoted in the Farmers' Magazine, Vol. ix.. No. 5, Third Series,) 

 after many careful observations, comes to the conclusion, First. 

 That the growth of grass is always proportionate to the heat of 

 the air, if a sufficiency of moisture be present in the atmosphere. 

 Second. That in the climate of England the moisture present 

 is rarely sufficient to allow the temperature to have full effect, 

 when that temperature exceads 5G°, but that if moisture be 

 artificially supplied, as by irrigation, to catch water meadows, 

 that then vegetation will still proceed in proportion to the heat. 

 Third. That when the temperature of the air is between 36° 

 and 41°, the grass will only vegetate with a fifth part of the 

 force that it will when the temperature is 56°. Thus the land 

 that will keep ten sheep per acre in the latter case, will only 

 k)ep two in he forme;. That Irom 41° to 46° its gro .a th is 

 two-fifths, or double that of its growth when the temperature 

 is under 41°, and it will then ke p four sheep instead of two. 

 Again, from 46° to 5j°, its growth will ri; e to seven-" nths, or 

 it will keep on the same ground from five to seven sheep, and 

 from 50° to 6Q°, it gener.ll — unless assisted by an artificial 

 addition of moisture — arrives at its maximum ; but if the 

 month of June be very moist, it will cjnt nue to grow with an 

 increase of force up to 60°. 



Our climate is very different from that of England. The 

 evaporation from the soil is ordinarily very much more rapid, 

 and the actual amount of moisture in the air is greater, since 

 it is well established that the evaporation is in proportion to the 

 height of the temperature and the extent of water or land sur- 

 face ; that in the temperate zones it amounts to about thirty- 

 seven inches a year, while in the tropics it rises to from ninety 



