26 ANNUAL OF SCIENTIFIC DISCOVERY. 



of mineral ingredients may be put forward as a motive for further trials, the 

 utility of ammoniacal substances in all their several forms is at the same time 

 distinctly admitted. Still the practical question remains, whether, admitting 

 the theoretical truth of Baron Liebig's position, a larger expenditure of capital 

 will not be required for bringing a given farm into a condition to dispense with 

 ammoniacal manures, than for procuring those materials which contain that 

 ingredient ready for use. And here experimental researches, such as those 

 conducted on so extended and liberal a scale by Mr. Lawes and Dr. Gilbert, 

 come in aid of theory. They stand, as it were, midway between the abstract 

 principles winch science points out to the farmer, and the traditional usages 

 with respect to his art which have been handed down to him from one gene- 

 ration to another. They bear the same relation to the farmer, which the 

 records of the clinical practice in a large infirmary do to the general principles 

 of medicine expounded by the modern physiologist. It is true, that the expe- 

 rience of a particular hospital may not at all times coincide with the anticipa- 

 tions which science holds out ; but this discrepancy only suggests to. us the 

 imperfections of our present knowledge, and it is not allowed to disturb the 

 confidence of the physician in principles already established on incontroverti- 

 ble evidence. On the contrary, whilst he modifies his practice from time to 

 time by the experience he has gained by actual observation, he feels at the 

 same time the fullest conviction, that these results will be found eventually 

 reconcilable with the general principles which a still more extended series of 

 induction may have established. I need not occupy your time by applying 

 the same method of proceeding to the recent researches alluded to, but I will 

 carry the analogy between the science of Agriculture and Therapeutics one 

 step further. You may recollect, that in a report on the progress of husban- 

 dry, drawn up some years ago by one of the most enlightened and zealous 

 promoters of the agricultural interest in Great Britain, it was asserted that 

 chemistry had done nothing for the farmer, except in teaching him to use sul- 

 phuric acid with his bones, and to take advantage of the refuse flux liquor for- 

 merly thrown away and wasted. Now a statement of this kind, although it 

 might be literally true in the narrow sense in which the author doubtless 

 intended it, namely, as referring merely to the introduction of new specifics 

 or recipes into farming was calculated, when put forth on such high authority, 

 to foster that tendency in the human mind to which we are all more or less 

 prone, that of sparing ourselves the trouble of thought and reflection in shap- 

 ing the course of our conduct, by leaning blindly upon certain rigid and 

 unvarying rules already chalked out to us by others. Grant that science has 

 as yet supplied us with only two infallible recipes for the improvement of our 

 land, the agricultural chemist may derive credit from the reflection, that medi- 

 cine too, since the days of Hippocrates, has lighted only upon two or three 

 specifics for the cure of disease ; and that the most enlightened physicians of the 

 present day, in the spirit which we would fain see actuating the leaders of the 

 agricultural body, depend not upon the efficacy of nostrums, but upon their 

 sagacity in referring the varying conditions of each case which comes before 

 them to those principles of physiology which modern science has established. 

 And has not science also unfolded principles which may be called in to aid and 



