60 Mr, Sopwith on tlie [March 9, 



was placed on the table, showing the basaltic rocks at the waterfall 

 of Cauldron Snout. Passing northward, and somewhat west of the 

 limits of the Northumberland coal-fields, the basalt is found near 

 Alnwick, in the pleasure-grounds of the Duke of Northumberland, 

 at Dunstanbrough Castle, Bamburgh Castle, Holy Island Castle, 

 and at Farn Islands. 



The production of the coal mines of the Northumberland and 

 Durham district now reaches an amount little, if any, short of 

 fourteen millions tons annually. In round numbers, and as con- 

 veying a general approximation, it may be considered that of this 

 quantity six millions are destined for London and the coast trade, 

 and about two and a half millions exported abroad ; the consump- 

 tion of coal for coke (inland, coast, and foreign) is about two and a 

 half millions ; colliery engines and workmen consume upwards of 

 a million tons ; and the ordinary local consumption of the district 

 may be taken at about two millions. Of this enormous quantity, a 

 conception can only be formed by reducing it to some other 

 standards of comparison, as for example : — This quantity of coal, if 

 formed into blocks of one cubic yard each, would cover about four 

 square miles ; and if the same quantity of coal be considered as 

 forming the coating of a road, one inch thick and six yards wide, it 

 would extend considerably more than four thousand miles. Blocks 

 of one cubic foot can be readily comprehended ; and if one person 

 were employed to count these blocks at the rate of three thousand 

 six hundred in every hour, and thirty-six thousand every day, it 

 would occupy him more than ten years to complete his task. 



The variable thickness of different coal-seams was adverted to, 

 and the number and thickness of the seams or beds of coal in the 

 North of England described. Several illustrations were shown 

 from an able work recently completed by Mr. Greenwell on Mine 

 Engineering. The thickness of the Newcastle seams varies from 

 an inch to five and a half feet ; the aggregate thickness of nearly 

 sixty seams amounts to about seventy-five feet, or nearly four per 

 cent, of the entire mass of strata. Nine only of these beds exceed 

 two and a half feet, and the aggregate quantity of workable coal 

 is, therefore, only about one-half of the above quantity. The depth 

 at which the mines are worked was shown by several examples, 

 varying from nearly three hundred fathoms (eighteen hundred feet) 

 at Monk-Wearmouth, to shallow pits, worked at a small depth from 

 the surface, near the outcrop of the coal. The detailed maps, by 

 Mr. J. W. Bell, of Newcastle, one of which was shown, exhibit 

 the boundaries of property in the coal field, and form a valuable 

 local record of the position and extent of the various collieries. 



The general situation and extent of the Lead mining district 

 was described by reference to the map, and a number of plans 

 and sections explained the manner in which mineral veins occur, 

 and the details of works by which access is had to them. Ac- 

 curate returns of the produce of lead and other minerals are now 



