OF AGRICULTURE. 27 



description was grown successively. Subsequent 

 examination of the soils further showed considerable 

 differences, dependent on the exhaustion by the dif- 

 ferent crops. 



Dr. Daubeny confined his illustrations and his dis- 

 cussions almost entirely to the mineral or ash-con- 

 stituents of the crops; thus following the lines of 

 argument current at the time. Although the facts 

 brought out are of interest, all subsequently acquired 

 evidence tends to show, that the benefits of rotation 

 are not explicable by exclusive reference to the dif- 

 ference in the description, and amounts, of the mineral 

 constituents which are taken up by the different crops. 



Among the most notable of Professor Daubeny' s 

 lectures, was a course of eight on Koman Husbandry, 

 which were afterwards published. 



These lectures evince considerable historical re- 

 search, and are of much interest independently of 

 the facts relating to the Agriculture of the Ancients 

 which they bring to light. But their chief interest 

 to the agricultural student of the present day is to 

 be found in the evidence, discernible between the 

 lines, that certain practices then adopted for the 

 increase of the products obtained from the land, 

 are still recognised as effective, though, in some cases, 

 the precise explanation of the benefits derived yet 

 remains a matter of controversy. Thus, although no 

 fixed rotations of crops seem to have been adopted, 

 yet the occasional growth of plants of the Legu- 

 minous family was had recourse to, and recognised as 

 a means of increasing the growth of the gramineous 

 crops with which they were alternated. 



Again, the evidence of both Columella and Virgil 

 goes to show, that the fertility of soils was then 

 attributed to the accumulations from previous natural 



