HINDRANCES AND HELPS. 229 



what too loosely and rashly in his theories of applied 

 science. Naturally enough, confident in the results 

 of his own investigation, he entertains a certain con- 

 tempt for a merely empirical art , he undervalues the 

 experience and practices of its patrons, and proposes 

 to lay down a law for them, which, having scientific 

 truth for its basis, may work unvarying results. I 

 do not know how I can better illustrate this, than by 

 noticing some of the various theories which have 

 obtained, in respect to the fertilizing action of 

 gypsum. 



A fanner, for instance, finds himself within easy 

 reach of a large supply of this salt, and being chemi- 

 cally inclined, he sets himself to the task of reading 

 what has been written on the subject, in the hope, 

 possibly, of astounding the neighbors, and glutting 

 the corn market. 



At the outset I may remark, that farm-experience 

 has as yet found no law by which to govern the 

 application of gypsum ; on one field it succeeds ; in 

 another, to all appearance precisely the same, it fails ; 

 at one time it would seem as if its efficacy depended 

 on showers following closely upon its application ; 

 in other seasons, showers lose their effect. In one 

 locality, a few bushels to the acre work strange 

 improvement, and in another, fifty bushels work no 

 change whatever. Now it is a hill pasture that de- 



