V. 



c- 



PLATE 



V- 



Rep 



a iis the upper ftratum, fuppofe of marie ; c dh the 



fecond ftratum, fuppofe of fand ; ef 

 It is defigned to fhew, that in boring holes through the upper ftraium to find that 

 beneath it, they fhould be formed perpendicular to the fide of the mountain, and not 

 perpendicular to the horizon, as is tlie common pra6tice, as by thofe means the 



Shorter 



Sedl. XL I. 5 



C'hr- 



<'* 



a 



^ 



<5 



f?> 



/ 



r 

 \ 



\ 



•" 



\ 



