6 



ingly complex. The most experienced eye is unable to judge 

 with certainty of a quality of a soil or marl, or the adapted- 

 ness of the one to improve the other, by the eye, or any super- 

 ficial examination alone. Nothing short of a complete and 

 careful chemical analysis, and extensive comparisons of the 

 results with others, and with previous experience, can give 

 them that practical value and full reliability as guides to 

 the practical man, which in the present state of science he 

 does, and has a right to expect. Investigations of this kind 

 are not a matter of an hour or a day ; they require time, 

 extreme care, and the best means of research not only in 

 the laboratory, but quite as much in the field. 



To the minds of those not specially acquainted with the 

 subject, the absolute necessity of extreme accuracy, care and 

 conscientiousness in the execution especially of the agri- 

 cultural part of the work may perhaps be best illustrated by 

 reference to the well known fact, that some of the most im- 

 portant ingredients of soils, the withdrawal of which renders 

 them absolutely sterile, are generally present in them in such 

 minute quantities, that a careless analyst might overlook 

 them altogether. And no less may he utterly fail in detect- 

 ing the characteristic differences between various kinds of 

 soil, by committing an error which in many other cases 

 where chemistry is applied to practice, would be totally in- 

 significant. An analysis of soil, carelessly made, is useless? 

 and worse than useless. And even a correct analysis may be 

 useless, unless all the natural conditions influencing the soil 

 analyzed, in its place of occurrence, have been correctly ob- 

 served in the field. And what is true of soils, is equally 

 so in its application to marls, which are intended to improve 

 the soil ; if incorrectly chosen, they may do the very con- 

 trary. 



Again : in a level country, where the underground strata 

 rarely appears on the surface, while their character is ex- 

 tremely variable, it is not an easy matter to ascertain cor- 

 rectly their geological features, which are of the greatest 

 importance with reference to the digging or boring of wells. 



