37 



*. d. 

 On No. 1, The average gross produce on 6 acres, 



is, per acre, 180 



,, No. 2, do. do. .246 



,, No. 3, do. do. .400 



,, No. 4, do. do. .634 



The foregoing are not supposititious rotations. Within 

 the circle of an hour's walk, in some of the maritime 

 districts of the county of Antrim, where the line of coast 

 is skirted by mountain scenery, each of them may be 

 observed in actual practice. Such comparisons exemplify 

 the immense difference between soils. They show that 

 inferior lands are the dearest, whatever rent they are 

 charged with ; and they furnish the valuator with certain 

 data to guide him in his valuations. He should not, 

 however, trust wholly to his theoretic knowledge of 

 alternate husbandry in these calculations, but inquire 

 diligently, and ascertain from intelligent farmers, in every 

 district where he labours, what is their actual practice. 

 By this means he will be made sensible of local peculiari- 

 ties in the soil, climate, situation, and markets, of which 

 every skilful agriculturist would gladly avail himself, to 

 modify his preconceived notions of the best rotations. 



IV. MODE OF COMPUTING THE CONTENTS OF LAND. 



The superficial contents of land, in the British isles, are 

 always expressed in acres, roods, and perches each acre 

 containing 4 roods, and each rood 40 perches. 



In measuring land, the principal instrument used is a 

 chain of 100 links 4 perches long. One square chain 

 contains 10,000 links, or 16 perches; and 10 square 

 chains, containing 100,000 links, or 160 perches, are equal 

 to 1 acre. 



In field practice, the length of lines is expressed in 

 chains and links. A line 18 perches long, would be 

 marked by a surveyor, as 4 '50 i.e., 4 chains and 50 

 links, and the calculations are all made in the same terms. 

 Thus, suppose a field to be an exact square of 4 chains 

 and 50 links on each side, then, by multiplying 450 on 

 450, the total amount is 202,500 square links. 



