1867.J Mineralogy, Mining, and Metallurgy. 423 



side. It appears that the " Georgie " — that is Stephenson's lamp — 

 and Clanney's, were not found to be any safer than the Davy ; and 

 the Belgian lamps Eloin's and Mueseler's were equally liable, 

 under certain conditions, to explosion. A few years since those 

 lamps were what they professed to be — with the currents of air 

 travelling at the rates which were then common, there was 

 nothing to be apprehended. Yentilation has been greatly im- 

 proved, and the quantity of air now driven through a colliery is 

 nearly double that which was considered necessary a few years 

 since. Consequently a lamp is now exposed, especially in our best 

 collieries, to a current having twice the velocity of the air to which 

 it was formerly exposed. This improved rate of ventilation renders, 

 according to the experiments at the Hetton colliery, all existing 

 safety lamps dangerous whenever an atmosphere of fire-damp pre- 

 vails. These experiments must be repeated under all conditions ; 

 and the safety lamps, which are evidently correct in principle, must 

 be modified to meet the improved conditions of ventilation. 



Such paragraphs as the following are from time to time 

 appearing in the newspapers relative to the extension of our coal- 

 fields. 



"The question as to whether coal may not be found under 

 other formations than those acknowledged and defined, is having a 

 practical solution in the extreme south of Derbyshire, at a point 

 where it has been laid down on the geological map as being free 

 from anything of the hind." We are then told that at Coton 

 Park, a few miles from Gresley, a wealthy proprietary are sinking 

 in the expectation of reaching coal at a moderate depth ; and the 

 writer continues — " Should they be successful, of which there is a 

 strong probability, the finding of the coal cannot but have an 

 important bearing on the important question which the Eoyal 

 Commission is now investigating as to the extent of our coal- 

 fields." 



If the writer of this had been at the trouble to consult the 

 published evidence of the Geological Survey in regard to this very 

 district, he would have found, upon Horizontal Section, No. 52, a 

 well-defined plan of the strata and of the faults by which it has 

 been disturbed, with the following remark — " The coal-measures of 

 this area have not been proved, but the coal seams probably rise 

 toivards the west under the New Bed Sandstones, and in any case 

 their depths are influenced by the faults here marked." This 

 certainly does not confirm the writer's statement as given above, 

 but it proves that the existence of coal over this area is well known, 

 though the depth at which it will be found has yet to be 

 determined. 



A mine of Antimony of St. Mary-le-Plain, in the canton of 

 Massiac, in the department of Cantal, Central France, which was 



