Main Rail Way. — Geological Structure. 11 



plain is, by a machine, drawn the length of board, at a single move- 

 ment, and unavoidably produces a correct surface, which of course 

 fits another made in the same way. When the boards are nailed in 

 their places, they are pressed close together by machinery, and then 

 the nails are driven. There is also a machine for raising the boats 

 from the floor, one edge resting upon it, so that the workmen can go 

 under them. Although they will be soon disused in this place, they 

 may be useful elsewhere, and the ingenious contrivances by which 

 they are so rapidly constructed may be applicable in other cases. 



THE MAIN RAIL WAY. 



It has only one track, and is nine miles long to the mine, and 

 eight miles to the highest point ; its branches and sidling cuts are four 

 and a half miles more ; it descends at the rate of 100 feet in a mile." 

 There are two places for turning out, made, as usual, by a Curved 

 rail road lying against the main one, and forming an irregular segment 

 of a circle resting upon its chord. The rail way is of timber, sup- 

 ported by cross pieces of the same, and the rail is shod on the up- 

 per and inner edge with flat bar iron. It was laid down with sur- 

 prising rapidity, for it was actually in use within a little more than 

 three months from the time when the timber was growing in the for- 

 est.* Its cost was something over ^'3000 a mile. 



A traveller makes the excursion to the mine with very little fatigue, 

 in a pleasure car which is drawn on the rail way by horses, and the 

 journey up occupies only one hour. You can descend into the mine 

 in the car, but it is usual to leave it at the summit level and descend 

 on foot. 



This great excavation is at the termination, and nearly on the sum- 

 mit of the Mauch Chunk mountain. Nothing can be more obvious 

 and intelligible than this mine. They have removed the soil and 

 upper surface of loose materials, and come directly down upon the 

 coal or upon the rocks which cover it. 



GEOLOGICAL STKUCTURE. 



The geological structure of this coal formation is extremely simplev 

 As far as we saw, the upper rock is a sandstone, or a fragmentary 

 aggregate, of which the parts are more or less coarse or fine in dif- 

 ferent situations. In this region there is much puddingstone and 

 conglomerate, and much that would probably be called graywacke, 



" Begun in January, 1827, and finished in May following; more than 100,000 tons 

 of coal have been transported upon it, and its use, during the time of the year when 

 the canal was open, has never been interrupted, a single weekVsince it was constructed. 



