24" THIRD REPORT — 1833. 



be found in them ; where they are inclosed by the gritstones, 

 there they become more productive ; but it is in one of the beds 

 of hmestone, and one only, that the great deposit of lead ore is 

 to be found. 



In the great mining field of Alstone Moor, this bed is called 

 the great limestone, and yet its thickness is only about 23 

 yards out of the 280 which the series of lead measures occupy; 

 and notwithstanding this, four-fifths of all the lead ore found 

 in the district is derived from such parts of the veins as are 

 inclosed by this particular stratum. 



The veins equally passing through the other beds, and traced 

 by innumerable workings through them, are yet only rich in 

 metallic treasure where they repose in this favoured stratum *. 



Though perhaps few cases are so striking as this, yet it is 

 evident that the same thing takes place to a certain extent 

 with all the metals, in all rocks and in all countries. 



If it is a fact and correctly stated, it must be considei'ed in 

 reference to the theories propounded to us, and it seems directly 

 opposed to the doctrine of forcible injection; but it may admit 

 of probable explanation by calling in certain affinities, either by 

 the advocates of precipitation from water, or by those who may 

 contend that sublimed vapours might be attracted to particular 

 spots. 



* To illustrate the comparative bearing of the different beds in the manor of 

 Alstone Moor, Mr. Thomas Dickinson, the Moor Master for Greenwich Hospi- 

 tal, extracted for me an exact account of the ore produced from each bed in all 

 the mines of the manor in the year 1822, which gave the following results: — 



Limestone Beds. — Great limestone 20,827 bings. 



Little limestone 287 



Four-fathom limestone 91 



Scar limestone 90 



Tyne bottom limestone 393 



— 21,688 



Gritstone Beds. — High slate sill 107 



Lower slate sill 289 



Firestone 262 



Pattinson's sill 259 



High coal sill 327 



Low coal sill 154 



Tuft 306 



Quarry hazel 44 



Nattrass Gill hazel 21 



, Six-fathom hazel 576 



Slaty hazel 18 



Hazel under scar limestone 2 



2,365 



Whole produce of the mines of the manor 24,053 bings. 



