276 Scientific Geology. 



A variety of causes led to the abandonment of these explorations : 

 but a few years since they were again resumed ; and through the 

 kindness of Dr. Thomas H. Webb, of Providence, I have before me 

 a letter addressed to that gentleman, from J. Clowes, the intelligent 

 agent employed to superintend this second exploration ; from which 

 I derive the following facts respecting the anthracite of Portsmouth. 

 The letter is dated February 18th, 1828 ; which appears to have been 

 about the time when the work was the second time abandoned. 



The quantity of anthracite raised at these mines in 1827, by 20 

 men and five boys, was 2200 tons, and an equal quantity of slack : 

 that is, very small coal and dust. The former sold at the mine for 

 $4 1-2 per ton, of 2240 pounds ; and the slack for one dollar per ton. 

 The slack was used for burning lime and bricks. The best coal 

 was mostly employed for fires in families, except in New York, 

 where it was used for making glass ; for generating steam under the 

 common circular or round boiler ; for blacksmiths, and in general for 

 any purpose where anthracites are employed. 



The agent regards these mines as capable of furnishing an inex- 

 haustible supply. He represents the coal as occurring in veins ; but 

 his descriptions apply rather to beds ; and I am almost certain that 

 it occurs in beds. Six of these have been exposed ; and more than 

 30 are said to exist in that part of Rhode Island. Their direction is 

 south west and northeast, and they dip southeast from 40 to 90. 



The following are the strata that were penetrated in sinking a wa- 

 ter shaft, or engine pit, 87 feet ; and in fifteen other places they were 

 found to be very similar. 



Sand and gravel, . . . . 9 feet. 

 Dark colored slate, . : > *. . .12 

 Hard compact graywacke, . . 23 

 Soft black slate, .... 4 



Hard brown slate, . . V; '?' 5 

 Soft fine gray slate, .... I 

 Very hard brown slate, . . .17 

 Gray freestone, . "'./' . . .12 

 Coal, . 4 



Vegetable remains were found only in one of these excavations, 

 about nineteen feet below the surface. 



The failure of the mining operations in Portsmouth, between the 



years 1809 and 1816, resulted, according to Mr. Clowes, from two 



, general causes : 1 . A want of practical skill in those who conducted 



