Explanations. Fia. II. 



a?, x Stream, in a small natural ravine, on the sides of which some of the 

 marl was exposed, at the out-cropping. 



A, A the first range of marl, successively uncovered and excavated in the 

 small perpendicular pits 1, 2, 3, 4, &c. 



B, B, and C, C second and third ranges of diggings, in like manner, but 

 increased in sizes of pits. 



D, D, D at first the natural surface of ground (5 feet above the marl), on 

 which the marl was thrown out of the pits of range C ; and next after, 

 D, D, D, was the first range of graduated digging. 



c, d the upper part of D, 96 feet long, the overlay but partly removed at 

 first, so as to form an inclined plane for the roadway. The same de- 

 scending grade continued in excavating the marl from d to e e. 



c, e?, e, e narrow drain cut first down to, and afterwards into the marl, to 

 intercept spring water, and turn it into the stream x and thus to drain 

 the space D D. 



ff t g farm road, on level, opposite ranges D, E, F, G, rising from 5 to 6J 

 feet above the marl. 



A, k, h, h upper ends of roads successively used from the graduated dig- 

 gings. 



0) o lower ends of descending roadways in the marl. 



E, F, G successive ranges, uncovered and excavated in graduated diggings, 

 similar to D, but increased In extent. 



H, H range 36 feet wide, uncovered for next working and less than half 

 the marl of which was excavated, when my operations at this place were 

 finally closed in December, 1850. 



N. B. The Fig. II. is drawn on the scale of 80 feet to the inch, for the 

 dimensions of ranges, and the general outline and space. But small sizes, 

 and distances, as width of drains, &c., are necessarily irregular, and much 

 larger than the scale. 



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