ADVERTISEMENT. 



To those Gentlemen who have so kindly favoured me with in- 

 formation on the subjects connected with this Work, I beg leave 

 to return my sincere thanks. In particular, my best acknowledg- 

 ments are due 



To Sir HUMPHRY DAVY, for his very kind and liberal assist- 

 ance in furnishing the simple chemical process, from which I 

 derived confidence to attempt to realize the idea, first suggested 

 by His Grace the Duke of Bedford, of ascertaining the nutri- 

 tive powers of the different grasses, by the aids of chemistry ; 

 and from the admirable simplicity of his details of the process 

 for analyzing soils, and vegetable substances, given in his impor- 

 tant work on Agricultural Chemistry, I have been enabled to 

 execute this difficult part of the inquiry. 



To THOMAS GREG, Esq. of Coles, for many valuable commu- 

 nications on the most important practical parts of the Work ; and 

 his kindness on every occasion of inquiry on the subject of it. 



To JAMES SOWERBY, Esq. F.L.S. for his assistance in pro- 

 moting the knowledge of the different agricultural earths, by 

 undertaking to supply those gentlemen who are interested in the 

 inquiry, with cabinet specimens of the whole of the different 

 soils employed in this series of experiments. 



I am likewise much indebted to A. WILSON, Esq. of Hurd- 

 wick House, Tavistock, for a variety of useful practical informa- 

 tion, which he could so well supply. 



To Mr. THOMAS GIBBS, Seedsman to the Board of Agricul- 

 ture, I am indebted for information respecting those plants more 

 recently introduced to the Agriculturist, and which I could not 

 otherwise have obtained ; for a collection of the different soils 

 in the vicinity of London, with their local names ; and for his 

 willingness, on all occasions, to communicate useful information 

 on the subject of the grasses. 



Since the folio edition of this Work was printed, and during the 

 progress of this enlarged one, I have been laid under the greatest 



