36 Subsoil. 



On the whole, there is a most intimate connexion be- 

 tween the soil and subsoil ; and the fertility of the former, 

 essentially depends on the quality of the latter. It is indeed 

 evident, that the nature of the subsoil, as well as of the 

 soil, must be ascertained, before a farmer can, with pro- 

 priety, select his plants, determine on the species of manure 

 to be employed, or arrange his course of cultivation ( I * 7 ). 

 Such investigations therefore, are of the highest import- 

 ance to agricultural economy. They may be the means of 

 explaining peculiarities and anomalies, which cannot at pre- 

 sent be accounted for, and may suggest the best methods 

 of improving a soil, by correcting the defects in its con- 

 stitution, and removing the causes of its sterility. An in- 

 quiry, conducted on a great scale, and aided by the pub- 

 lic, might thus lay a basis of general improvement, incom- 

 parably superior to any that has hitherto been attempt- 

 ed (" 8 ). 



SECT. IV. Elevation. 



THE value of a farm must likewise depend upon its ele- 

 vation. Where the ground is high, it must be more diffi- 

 cult and expensive to convey manure to it, and to carry on 

 the other operations of husbandry. Land also, in the same 

 parallel of latitude, other circumstances being nearly si- 

 milar, is always more valuable, in proportion to the com- 

 parative lovvness of its situation, in consequence of the su- 

 perior quality of its produce. In the higher districts, the 

 herbage is less succulent and nourishing, and the reproduc- 

 tion slower, when the land is in grass ; while the grain is 

 less plump, runs more to straw, ripens less perfectly, and 

 is later in coming to maturity ( ia9 ). 



It has been calculated, that in Great Britain, sixty yards 

 of elevation in the land, are equal to a degree of latitude , 

 or, in other words, that sixty yards perpendicularly higher, 

 are, in respect of climate, equal to a degree more to the 

 north ( I3 ). 



Many extensive countries have no perceptible rise. These 

 have their advantages, from uniformity of soil, where it is 

 rich. In other districts, the surface is of a waving descrip- 

 tion ; an inequality which contributes much to the ornament 

 of the country, by the agreeable relief which the eye con- 

 stantly meets with, in the change of object, while the 

 declivity which prevails more or less in every field, is fa- 



