328 



M I N E. 



Mines of end and a female screw at the other ; these are what are 

 Coa 1 - named the common rods. The chissels for boring are 

 Boi-hi" r~' e 'ghteen inches in length, and are from two inches and 

 1 a half to three inches and a quarter in breadth at the cut- 

 ting edge, faced with the best steel ; with these one short 

 rod is connected, called the double box-rod, to which the 

 chissel is screwed. It is also eighteen inches long, so 

 that the chissel and box rod together, form a three feet 

 length equal to the common rods. There are also three 

 short rods, named cut rods of a foot, eighteen inches, 

 and two feet in length, which are attached to the 

 brace head, to render the height above the mouth of 

 the bore suitable for the men to work the rods with 

 effect ; by this arrangement, the whole set of rods di- 

 vides easily and accurately into yards and fathoms, for 

 the more correctly keeping a journal of the strata 

 passed through. What is termed the brace-head rod is 

 eighteen inches long, having two large eyes at the top, 

 set at right angles to each other, through which arms 

 of wood are put, by which the men lift and turn the 

 rods in boring, There are besides a number of other 

 instruments connected with the boring rods, viz. 



Wimbles, of various kinds. 



Sludgers. 



Rounders. 



These are occasionally attached to the rods, as after 

 described. There are also keys of different kinds for 

 supporting the rods, and unscrewing them when draw- 

 ing them up, or letting them down into the bore hole ; 

 and when triangles are used so as only to unscrew 

 four or five fathoms of rods at a time, topits or top- 

 pieces are used for each length of rods so cut, and an 

 instrument, named the runner, is used for taking hold 

 of the topits. Besides these, there are several instru- 

 ments named beches, with contrivances for catching 

 hold of the rods when they break down in the bore, 

 which is not an (infrequent occurrence. When bores 

 are only to be a few fathoms in depth, the whole ope- 

 ration is performed by manual strength ; but when a 

 deep bore of any consequence is to be made, a set of 

 lofty triangles of wood is placed over the bore- hole, 

 with a pulley at top, through which a rope is passed ; 

 one end is connected with a crane or windlas at the 

 surface, to the other end, an oval iron ring, named a 

 runner, is attached ; by these means the rods are drawn 

 up and lowered down with great facility. 



In England, particularly in the Newcastle district, 

 there are professional master-borers, who undertake to 

 put down bores for coal, and give a precise journal of 

 the strata passed through. The average price of bor- 

 ing in England and Scotland, where no uncommon 

 difficulties occur, is six shillings for the first five fa- 

 thoms, and an increase of six shillings each fathom for 

 every additional five fathoms, viz. 



1 st 5 fathoms 

 2d 5 do. 

 3d 5 do. 

 4th 5 do. 



20 Fathoms. 



6s. 

 12s. 

 18s. 

 24s. 



1 10 

 300 

 4 10 

 600 



15 



In this manner the price increases regularly with 

 the depth ; and in all common cases the master-borer 

 finds and upholds the boring, rods, but there are in- 

 stances where the price is considerably higher than 

 the above rate. 



In Scotland, boring for coal is scarcely known as a 

 profession, but there are master sinkers who occasion- 



ally bore, and who perform the operation -with accu- Mines of 

 racy. Coal 



The boring tools are represented in Plate CCCXC. 

 Fig. 1. in progressive numbers, viz. 



No. 1. The brace head. PLATE 



2. Common rod. cccxc. 



3. Double box-rod. *''6- * 



4. Common chissel. 



5. Indented chissel. 



6. Do. 



7. Cross-mouthed chissel. 



8. Wimble. " 



9. Sludger. 



10. Rounder. 



1 1 . Key for supporting the rods at the mouth of 

 the bore. 



12. Key for screwing together and unscrewing 

 the rods. 



13. Topit. 



14. Beche. 



15. Runner. 



16. Tongued chissel. 



17. Right-handed worm-screw. 



18. Left handed do. 



19. Finger grip. 



The mode of conducting a series of bores in explor- 

 ing the strata for coal, is next to be explained. 



Fig. 2. represents a district of country, in which, PLATE ; 

 after a regular survey, coal strata, and the appearances cccxc* 

 of coal, have been found, having an evident dip to the F 'S- 2> 

 south, as represented in the Figure. In this case, a con- 

 venient spot should be chosen upon the north part of 

 the district to be explored, in order that the different 

 bores may be carried southwards in the line of dip ; 

 the first bore is therefore put down at No. 1. suppose 

 to the depth of sixty yards. In this depth it is probable 

 many varieties and alternations of the strata will be 

 passed through, as exemplified in the sections of the 

 strata ; but, for the sake of perspicuity, only a few 

 strata are shewn in the figure, which strata are dis- 

 tinctly inserted in a journal as to their quality and 

 thickness, and specimens of each carefully kept. The 

 bore No. 1. passes through the strata d, c, It, a, without 

 finding any coal. And as in proving a district with a re- 

 gular series of bores, it is more economical to do so by 

 means of bores of a moderate depth, than with very 

 deep ones, which are attended with great expence, 

 provided there be no particular difficulty in passing 

 through the alluvial cover, which might render a num- 

 ber of bores very expensive. Suppose that, in the 

 first instance, bores of sixty yards deep are resolved 

 upon, as at No. 1. before mentioned, and that the dip 

 of the strata is 1 in 10, the consideration then is, at 

 what distance from No. 1. bore southward, will a se- 

 cond bore at the same depth strike the first stratum d 

 found at No. 1. ? The rule is, multiply the depth of 

 the bore by the dip, viz. 60 by 10 gives 600 yards, 

 which is the distance required. In this manner the 

 bores No. 2, 3, 4, and 5, are successively placed, with 

 this particular exception, however, that the point of 

 surface where the first bore is put down must be con- 

 sidered as the point of level to which the top of all 

 the other bores relate. If therefore the top of No. 2. 

 bore is 10 yards higher than the top of No. 1, that ad- 

 ditional depth must be added to the bore ere it can be 

 expected to reach the stratum d. On the other hand, 

 if the top of any succeeding bore is under the level of 

 the top of No. 1. bore, suppose 20 yards, that bore 



