461 



In fcaion 138, Mr. Playfair tells us, that Mr. Kirwati makes a diC 

 tinftion between wood coal, " in which the ligneous ftruclure is fo appa- 

 " rent as to leave no doubt of its vegetable origin ; and mineral coal, 



" in which no fuch ftruclure can be difcovered." Thefe two fpecies 



of coal, Mr. Playfair fays, " the Huttonian theory confiders is gradations 

 " of the fame fubftance." 



And in feftion 145, accounting for the fituation of a bed of coal, he 

 fays, " It is part of a ftratum of coal which has been dcpofited, 

 " like all others, at the bottom of the fea." 



Mr. Playfair Ihould tell us, how the trees and vegetables of a former 

 continent, have been able to preferve their fibrous and ligneous ftru£turc, 

 after paffing from one world to another through a procefs of decay, dt- 

 compofition, and comminution ; aifo, in what form they travelled the long 

 journey he obliges them to take, previous to their depofition at the bot- 

 tom of the fea. 



Similar difEculties attend the formation of calcareous ftrata, if we 

 adopt the Huttonian theory; for Mr. P/ayfair fays, (feclion 2d.) " Thefe 

 " ftrata often contain fliells, corals, and other exuvias of marine 

 " animals, in fo great abundance that they appear to be compofed of 

 " no other materials." 



And he tells us (feclion 402,) *' that all thefe, and even bodies of 

 " fifli and amphibious animals, now converted into flone, are parts of 

 " animals not of the prefent, but of the preceding world ; yet neither 

 he, nor Dr. Huttcn, tells us, how thefe fhells and bodies (often quite 

 perfed) preferved themfelves entire, in fuch a fcene of decay and 

 diffolution, as by their account muft have intervened in the change 

 from one world to another ; nor do they tell us by what means thefe 

 exuvioe were accumulated together, fo as to form intire ftrata. 



Were I to purfue tljis mode of difcuffion, and examine feverally 

 the different ftrata compofing the fuperficial parts of our globe, I 

 have little doubt but that the refult would be, that not one of 



them 



