88 Dtt THOMSON ON THE STRATA OF BERWICKSHIRE. 



near Grcenlaw-wells, that I am inclined to attribute the position of the 

 fossil tooth, which was found by one of our members, the Rev. Mr 

 Knight of Ford. The rocks at Ford and at Greenlaw- wells seem to ap- 

 proach each other in their composition, and both are near the surface. 

 Dr Grant, to whom I shewed the specimen, was of opinion that it be- 

 longed to a fish. It consists essentially of phosphate of lime, but effer- 

 vesces when it is touched with acid. The minuteness of the size of the 

 specimen, however, has prevented me from obtaining any satisfactory 

 results in reference to its quantitative analysis. 



Dr Johnston informs me, that the Lepidodendron Sternbergii has 

 also been observed at Ford, in the same sandstone, and impressions of 

 ferns (Sphenapteris ?). The position of the locality where these re- 

 mains are observed, is about two hundred yards from the mouth of a 

 coal shaft. 



The sandstone consists of a yellow calcareous basis, mixed with clay, 

 which serves to agglutinate irregular grains of white quartz, and exhibits 

 cavities lined with carbonaceous matter. The Greenlaw-wells sandstone 

 is likewise yellow, coarse, and consists of large grains. 



The Cooper-eye coal, although thin, when compared with coal beds in 

 other places, forms a good burning material. The levels formed during 

 its working are on an average 3 feet high. The coal is removed be- 

 tween two levels, and its place supplied by the limestone, which lies on 

 both sides of the coal. The immense pressure frequently crushes these 

 supports, and when any considerable quantity of country has been 

 mined, the surface sinks. The effect of this subterraneous quarrying is 

 very visible upon Duddo Tower, which has been rent from top to bot- 

 tom, in consequence of being undermined, notwithstanding that it is si- 

 tuated upon a considerable eminence. In traversing the different levels 

 I observed in one place a rent, the opposite surfaces of which appeared 

 brilliantly polished. I found, upon attending minutely to the adjoining 

 strata, that this was caused by one portion having subsided, while the 

 corresponding part had remained stationary. The consequence had been 

 violent pressure upon both surfaces during the subsidence of the former- 



I made many inquiries with regard to the occurrence of accidents in 

 the mines in this neighbourhood, and learned that they were very uncom- 

 mon. Inflammable air or carburetted hydrogen never appears, its occur- 

 rence being confined to deep mines. The only inconveniences arise from 

 bad ventilation when the levels have been driven to a great extent, and the 

 occasional disengagement of carbonic acid, which takes possession of the 

 extremity of a level, and cannot readily be expelled. A man was lately 

 killed by the influence of the latter cause. The coniequence of the ra- 

 rity of these accidents is, that no precautions are deemed necessary for the 

 safety of the miners. No safety -lamps are employed, a candle stuck in 

 a piece of clay sufficing for all necessary purposes. The name of a Davy 

 lamp is not known, except to those colliers who ha vo worked in the New 



