55 Agriculture. [Chap. VIIL 



Tlie general use of Marie, I J me, Chalk, and va- 

 rious combinations of calcareous matter, as means 

 of increasing the fertility of the soil, is chiefly of 

 modern date. And even with respect to these, and 

 such other m.anures as were in a degree known and 

 employed in ancient times, the mode of their ope- 

 ration, the best methods of aj^plying them, and the 

 various circumstances which should attend the ap- 

 plication, have been incomparably better under- 

 stood, within a iew years ])ast, than in any former 

 jjeriod. The most scientific and satisfactor}" mo- 

 dern writers on manures, in general, are Dundo- 

 nald, Middleton, Darwin-, and lennant, of Great 

 Britain; Kir^van, of Ireland; Parmentier, of France; 

 liuckert and von Uslar, of Germany; and Eller, 

 AV'allerius, and Gyllenborg, of Sweden. 



The influence o^ Light on growing vegetables has 

 also been investigated with great success by many 

 modern philosophers. Among these Hales, Priestley, 

 abbeXessier, Ingenhousz, andSennebier, are entitled 

 to particular distinction. From the experim.ents 

 of these philosophers, it appears that this subtle 

 lluid has a powerful effect on the colour of vege- 

 tables; that, when exposed to its influence, it en- 

 ables them to yield pure air; and that it converts 

 many substances, wliich would otherwise become pu-^ 

 trid and oifensive, into wholesome food for plants. 



The efiicacy of Electricity in forvv^arding the 

 gemiination and growth of plants was discovered 

 and satisfactorily established by the philosophers of 

 the eighteenth century. It was before remarked 

 I hat Mr. Mainibray, of Edinburgh, was the first who 

 applied electricity to this object. He was followcfl 

 by the abbe Nollet, Mr. Jallabcrt, M. Boze, and 



