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experience, and the philosophy of reason, are often at vari- 

 ance. 



One very important circumstance in all experiments upon 

 the produce of land, is the nature of the soil. Perfect definite- 

 ness, however, in the description of soils, is not attainable ; be- 

 cause they pass into one another insensibly. The rules adopted 

 by Sir H. Davy on this subject, will, nevertheless, furnish us 

 with convenient landmarks. *' The term sandy soil," says he, 

 " should never be appHed to any soil that does not contain at least 

 7-8 of sand. Sandy soils that effervesce with acids, should be 

 distinguished by the name of calcareous sandy soils, to distinguish 

 them from those that are siliceous. The term clayey soil, should 

 not be applied to any land which contains less than 1-6 of im- 

 palpable earthy matter, not considerably effervescing with 

 acids. The word loam should be limited to soils containing at 

 least one-third of impalpable earthy matters, copiously efferves- 

 cing with acids. A soil to be considered as peaty, ought to con- 

 tain at least one-half of vegetable matter." 



Suppose the experiment relate to the application of manures. 

 To judge of their effect, we should know the nature of the soil ; 

 the season of the year in which they were applied ; the state of 

 the weather at the time ; whether wet, or dry; cold, or warm ; 

 clear, or cloudy ; whether decomposition is just begun, or has 

 proceeded far; whether spread uniformly over the surface, or 

 otherwise; whether ploughed in immediately, or not; and the 

 state of the weather subsequently. 



In the paring and burning of lands — processes but seldom at- 

 tempted among us — the character of the soil is a circumstance 

 of prime importance; whether recently brought under cultiva- 

 tion — whether sandy, clayey, mossy, or peaty; whether natural- 

 ly wet and cold, or warm and dry; whether drained previously 

 to the operation : the state of the weather at the time, and subse- 

 quently, &;c. Similar particulars should be noticed in fallowing. 



Suppose the process to be transplanting. Most obviously a mi- 

 nute account of the soil whence the plant was taken, and of that 

 into which it is introduced, is requisite. Also the state of the 

 weather ; the relative situation of the plant, in regard to the 



