46 Mr Menteath on the Geohgy of Nithsdale. 



to 50 of pure lime. In this lower post, are several small beds 

 of day or stone marl, contairting 10 per cent, of carbonate of 

 lime, with impressions of shells, and alternating with beds of lime- 

 stone, which have imbedded in them some very interesting organic 

 remains, several of which have been drawn and described by 

 Sowerby in his Mineral Conchology. The following are the 

 most curious : — Orthocerae, nautili, some spiral shells, pro- 

 docti, trilobites, ^nd corals. The knowledge of such petri- 

 factions has become more interesting, since it has been ascer- 

 tained by Mr Smith, the ingenious author of a Mineralogical 

 Map of England, that they may be often a means of identifying 

 strata. Advantage has been taken of these clay-beds to mine 

 the lower post of limestone. For some years the operations ol* 

 this mining have been extensively carried on, and these excava- 

 tions now exceed many hundred square yards. In proceeding 

 with these excavations, strong pillars of nearly 6 square yards in 

 thickness are left standing, as supports for the roof of the mine, 

 which is high enough to admit the miner to stand erect at his 

 work ; and between the pillars the space of 30 feet is excavated. 

 This limestone, which is of a reddish colour, being extremely 

 compact, requires the aid of gunpowder in working it. The 

 heart of these excavations is penetrated by an h-on railway, laid 

 upon an inclined plane, up which, to the top of the kiln, the 

 limestone is raised by a water-wheel ; and this way of working- 

 has been for several years adopted at Closeburn Lime Quariy. 



The great advantage of a command of water in carrying on 

 the operations of an extensive work, is here strikingly exempli- 

 fied. Having put in motion the machinery which draws the 

 waggons loaded with limestone up the inclined plane, the water 

 is made to pass on in a channel excavated in a clay bed, and de- 

 scending to a lower level, is made to fall upon another wheel, 

 which puts in motion the pumps that drain the mine, and at 

 the same time a mill for sawing timber. The water, after these 

 useful applications, is next conveyed away for irrigation. 



It is worthy of remark, that the clay-bed, in which the 

 water-channel is cut, is well adapted for making fire-bricks. 

 The kilns at Closeburn Works for burning lime, are lined with 

 the bricks made of this clay ; and they resist, without injury, 

 for a long time, the great heat to which they are exposed. 



