New Inftrutnentfor Mine'boring. 127 



VIII. 



Defcriplion of a new Injlrwntntfor repeating the Examination of the Strata which have been 

 penetrated by the common boring Injlrument ujed in Mine Works, By A, Baillbt, In^ 

 ■ Jpeilor of Mines, and Profejfor at the Mineral School at Paris*, 



jtxFTER remarking the great utility of boring, in order to afcertain the exiftence of 

 mineral fubftances, particularly coal at great depths, the author obferves, that it would be 

 of great advantage if this operation could be eafily repeated or verified. " It often 

 " happens," fays he, " that fome doubts remain concerning the nature, the thicknefs, or 

 " the pofitlon, of the principal mineral (Irata through which the borer has pafl'ed. This 

 ." uncertainty increafes when there is reafon to fufpeft the integrity of the perfons em- 

 " ployed; in which cafe there is but one method of removing the uncertainty, viz. to bore 

 " the fame excavation a fecond time with a tool of a larger diameter, and endeavour to 

 *' confirm the rcfults of the firft operation by obferving thofe of the fecond." The flow- 

 nefs, the expence, and the other inconveniences of this method, may eafily be imagined. 

 To avoid thefe the author propofes the ufe of an inftrumcnt, which he calls a verifier 

 (verificateur), which. is of ufe to take at any required depth in the hole or re<£tiform, a 

 famplc of the ground which exifts at that.fpot. This inftrument, reprefented at fig. i, 

 .plate 9, is compofed of two principal pieces ; a fuperior piece a b, in which there is a 

 cylindrical cavity opening below ; and another inferior piece c d, inferted in this cavity, 

 and tcrmiriating in a cone. 



Thefe two pieces are conneiSled together by means of two keys or pins e e, which pafs 

 through the upper piece, and occupy a circular groove e fin the lower piece. 



The upper piece contains two knives^ ^, let into its thicknefs, and fixed at their upper 

 extremity by a fcrew h, A gutter or groove/, of an helical form, is made from the lower 

 part of each blade, for the purpofe of conveying the fragments and powder fcraped oiF 

 by thefe knives into the cup or cavity of the lower piece k. 



When the apparatus is addrefled, the backs of the t\t'o knives touch each other at /, and 

 the point of the cone m lies in the angle formed by the flopes of the two knives. 



The extremity s of the inftrument terminates in a fcrew, which is not reprefented in 

 the prefent drawing, and the other extremity r likewife terminates in a fcrew ; fo that by 

 means of thefe the inftrument may be lodged in any part of an hole already bored. That 

 irs to fay, a rod of any required length may be fixed below itby means of the fcrew /, and 

 the other rods neceflary to lower it down, may be fc»-evved on above. 



• Communicated to the Philomathic Society, and infeited in their Bulletin, No. 39, in the !5th 

 republicHn year. 



»'*«; 



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