Book 11. AGRICULTURE UNDER VARIOUS CIRCUMSTANCES. 205 



and light ; the reason of which seems to be that the alternate action of heat and cold, 

 rain and ice, meliorates the soil and prepares it better for the nourishment of annuals 

 than it can well be in countries where the soil is not only harder naturally (for all coun- 

 tries that have long winters have soft soils), but more or less occupied by perennial weeds. 

 Insects, and vermin. In cold countries the insects are generally of that kind whose eggs 

 go through the processes of the larva and chrysalis state under water, and land reptiles 

 are generally rare. 



1 260. Elevation, when considerable, has an absolute influence on agriculture. The 

 most obvious effect is that of obliging the agriculturist to isolate his dwelling from 

 those of other cultivators or villagers in the plains, and to reside on his farm. This is 

 well exemplified in Switzerland and Norway. We have already noticed the judicious 

 reflections of Bakewell on the subject as referable to the former country (337.), and 

 have also referred to those of Dr. Clarke respecting Norway (602.). The latter author 

 has depicted these alpine farms, both witli his elegant pen and skilful pencil (Jig. 175). 



The farmeries are generally built with fir planks, and covered with birch bark and turf. 

 The inhabitants chiefly live by the dairy, and seldom see their neighbours or any human 

 being beyond their own fire-side, except on the Sunday mornings when they go to 

 church, and on the Sunday afternoons in summer xrhen they meet to dance (Jig. 176.) 

 and amuse themselves. 



1 26 1 . As elevation is known to lessen 

 temperature in regular gradation ac- 

 cording to the altitude above the sea, 

 its influence on plants and animals must 

 correspond. Three hundred feet in 

 height are considered nearly equal to 

 half a degree of latitude, and occasion 

 a difference of temperature of nearly 

 twelve degrees of Fahrenheit. Hence 

 it is that the agriculture of the temperate, 

 may sometimes be adopted in the torrid, 

 zone ; and that some of the mountains of 

 Jamaica will produce, between their base 

 and summit, almost all the plants of the world. Hence, also, that even in the limited 

 extent of the island of Britain, a given elevation on mountains in Devonshire will be 

 adapted for an agriculture different from that required by the same elevation on the 

 Cheviot, Grampian, or Sutherland mountains ; and while wheat ripens at six hundred feet 

 above the level of the sea in Cornwall, oats will hardly ripen at that height in the Western 

 Isles. 



1262. Elevation exposes plants and animals to the powerful operation of wind, and in 

 this respect must influence the disposition of the fields, fences, plantations, and buildings 

 of the agriculturist, as well as the plants and animals on the farm. It has some influence 

 also on the density of the air and the supplies of water and vapour, and even in these 

 respects must affect the character of the agriculture. In Switzerland and Norway the 

 upper mountain-farms are completely above the more dense strata of clouds, and their 



