a Theory of the Earth, 2^3 



or mountain, the volcanic origin of which may appear 

 donlnful. 



34. Situation of its ftrata. To afccnd to the fammit of 

 thofo which are incUncd ; to examine whether tliey have 

 not a crater, or veltiges of one, 



^^. To obfcrve, above all, whether, in departing from the 

 mod elevated point, there are found ftrata diverging in all 

 parts, and proceeding from that point as a centre. 



35. To fludy the chara6lers of the ftones which have been 

 cxpofcd to the a6lion of the fire, in order to diftinguith them 

 from other porous ftones, fuch as glandulous ftones or a- 

 mygdaloides. 



37, When thefe chara6lers are difcovered, to examine 

 whether, in the neighbourhood of the doubtful mountain, 

 there are found fcattercd ftones which txhibit the ftmie cha- 

 racters, and which feem to have proceeded from that moun- 

 tain, 



38. To obferve whether there are found, in the neighbour- 

 hood of the doubtful mountain, anv veftioe of the remains of 

 heat concealed in the bofom of the earth, as of tliermal, or 

 even acidulous waters. It is well known that thefe figns are 

 equivocal, but their combination with others may throw 

 fome weight into the fcale. 



38. A. Whether there exift certain proofs of alternate 

 depofits of lava or other volcanic productions, and of matters 

 accumulated or depofitcd by the fea. 



39. Among the ftones changed by the fire, to difco\'er 

 thofe which may be confidered as having been fubjedled to 

 the aftion of one ftratum of coal in deflagration, and which 

 the celebrated Werner calls pfendo-volcaiiic, and to diftin- 

 guifti them from thofe which have been fufed in a real volcano. 



40. Bafaltes; their forms in columns, in beds, round 

 maftes; their connexions, the relation which the bafaltes 

 of thefe different forms obferve with each other. 



41. The nature of thefe bafaltes: that of their texture, 

 •f the p(jinis which they contain, of the pores aitd empty 



S 4 or 



