[ i6i ] 



To find the inclination, three holes, each reaching to the bed 

 of coal, are bored at the diftance of fix hundred feet from each 

 other, forming an equilateral triangle, and the level and depth- of 

 each are taken. The higheft is the ftandard to which the diftance 

 downwards ©f the bed of coal under each hole is referred, that 

 which is moft diftant in depth from the ftandard being the loweft. 

 It is almoft needlefs to add, that the boring fhould be fkilfully 

 eondudled, in order that the holes be perfedly perpendicular. A 

 defcription of the moft improved earth-borer has lately been 

 tranflated from the German, and publifhed by Dodor Mc. Neviir 

 of this city *. 



In England beds of coal of lefs than two feet and an half in^ 

 thicknefs are judged not worth working, but in Germany none 

 exceeding fix inches are negleded. 



To- convey a fuller idea of the ftrata of earth or ftone that 

 generally accompany coal-mines, I fliall here add an account of 

 thofe that are found in the principal coal-mines of Europe. 



* The price of boring in England is five fliillings per fathom for the firft ten 

 fathoms, ten fliillings per fathom for the next five fathoms, fifteen ihillings per fathom- 

 for the next five, &c. 



ENGLAND, 



