for Manufacturing Caji Iron. «g 



Thefe galleries are in Scotland called the barrow roads. 

 Whenever the miner has arrived at the extremity of his 

 working, he turns round, and commences an excavation on 

 his right and left hand, proportioned to the rife and dip of 

 the ftone, to the extent of feveral yards on each ; the ac- 

 companying drift and rubbim are packed into the va- 

 cuity behind him : fliould there remain any fuperfluity un- 

 packed, if is wheeled to the mouth of the gallery alono- with 

 the iron-ftone. In this manner the miner returns, and 

 brings along with him the whole iron-ftone contained in 

 loo to 240 yards in length, and in 20 to 30 yard- in width. 

 The height of the gallery is commonly fo fmall, that the 

 miner is obliged to perform his work upon his fide : the 

 wheelers are likevvife obliged to pufli the barrow on all fours. 

 This fpecies of working is called under cover ; and the at- 

 tainment of a band of good iron-ftone, though only four 

 inches thick, will fufficiently defray the expence of the ope- 

 ration. It is here alio obvious, that this operation can onlv 

 be carried a certain length in the fame gallery, till fuch 

 time as the expence of wheeling out the ftone muft exceed 

 the value of that fliare of labour generally appropriated to it. 

 A more economical method is therefore indifpenfibly req - 

 lite. This is effected by finking a pit 160 to 200 yards far- 

 ther on the fame line of level. When the iron-ftone is 

 found, the miner fets off another gallery, or bar row r ad, 

 towards his former working, and continues till he meet the 

 termination of his old wajle : as formerly, he now begins his 

 retreat, and carries with him a fimilar portion of iron-ftone 

 from each fide of the gallery. The quantity of iron-ftone by 

 Weight obtained from fuch a working, depends entirely upon 

 its extent and the thicknefs of the band. A fquare yard of 

 iron-ftone containing 9 cubical feet, as it lays (Iratified, will 

 weigh from 1850 to 1900 pounds weight. ' The other lide 

 of the pit is next perforated, and the fame operation c 

 pkted. When the iron-ftone is thus exhauitcd, another pit 

 funk at a fimilar diftance from the termination of the fe- 



cond 



