VI.] ASPECT 117 



sunshine, the thermometer below the blackened soil will 

 register from one to four degrees higher temperature 

 than the other one beneath the uncoloured soil. Aspect 

 is also a matter of considerable importance — a field 

 sloping to the south, not only receives the sun's rays 

 both earlier in the morning and later in the evening, 

 than another field facing north, but also the intensity of 

 the rays upon a given area is greater. Since the sun is 

 never vertically overhead in this country, the area that 

 has to be covered and warmed by a given beam of sun 

 is smaller when it falls on ground sloping towards the 



Fig. 21. — Distribution of Sun's Rays upon Southerly 

 AND Northerly Slope. 



beam, Le. southwards, than when it slopes the other way. 

 The diagram, Fig. 21, shows on to how much smaller an 

 area the sunbeam AB is concentrated when the area 

 slopes towards instead of away from the beam. An 

 early soil should also be a sheltered one ; wind always 

 increases the evaporation from the soil, and therefore 

 reduces its temperature; the use of hedges and 

 screens of any kind is of value to the raiser of 

 early vegetables, provided he does not allow them to 

 keep the sun off his crops. Height above sea-level is 

 also a factor demanding consideration ; putting aside 



