26 KNOWLEDGE OF LOCAL PRACTICE. 



To the general nature of the soil, the local geology, the 

 springs, &c., I have already alluded. But he should know 

 also 



1. The kind of corn and root, or other crops usually culti- 

 vated in the district. 



2. The rotation in which these crops usually follow each 

 other, and the general reasons for its adoption. 



3. The manures usually employed ; how they are prepared ; 

 when, and how, and how often, and in what quantity, they are 

 applied. 



4. The state of cleanness, dryness, openness, &c., in which 

 the land and crops are usually kept. 



5. How the rearing and feeding of cattle is understood : to 

 what extent it is practised, and its influence upon the mode of 

 manuring, and the consequent condition of the land. 



6. Even the tenure of the land and the size of farms are 

 indispensable things to know. 



Here are numerous points beyond the sphere of a mere 

 chemist, whose mind must be greatly enlarged with kindred 

 information before he can give safe experimental advice to the 

 practical rent-paying farmer. 



Of course, in the following work, which contains general sug- 

 gestions for experiments in all localities, I cannot include such 

 as are especially adapted to given districts and farms, as if I 

 knew regarding them all the particulars above detailed. But 

 persons of skill, to whom these circumstances are all known, 

 will in each case select, from what this book contains, such recom- 

 mendations or suggestions as appear most suited to the circum- 

 stances, and will modify them as these circumstances may seem 

 to advise. 



4. Importance of local climatic knowledge. 



It will at once strike the reader that the bulk of the sugges- 

 tions offered in the following pages must be suited especially, if 

 not solely, to such climates as resemble generally that in which 

 we live. But among ourselves there are great diversities of 

 climate, the effect of which, in regard to experiments to be 

 made on a particular spot, ought carefully to be considered ; 



