Lesley.] *^ t Jan. 2 and Feb. 6, 



been left standing as sandstone strata ; while others having but little 

 sand remain as solid and massive limestone strata ; those which had an 

 excess of alumina are now in the condition of streaks, masses, or layers 

 of white or mottled clays ; and only such as were properly constituted 

 clay-sand-lime-iron deposits originally have so completely dissolved as to 

 permit the lime to flow off", and the iron to consolidate into ore. 



Every stage of this interesting operation, and every phase which it 

 presents in other parts of the Appalachian belt of the United States, from 

 Canada to Alabama, may be seen and studied in these old and extensive 

 ore banks of Pennsylvania Furnace. 



At first sight of the bank the ore deposit looks as if it were a grand wash 

 or swash of mingled clay and fine and coarse ore grains and balls, occupying 

 hollows, caverns and crevices in the surface of the earth and between the 

 8oli«d limestone rock ; and some of it undoubtedly has been thus carried 

 down into the enlarged cleavage partings of the limestones ; and into sink 

 holes and caverns formed by water courses ; where it now lies, or lay when 

 excavated, banked up against walls or faces of the undecomposed lime 

 rocks. But as a whole the ore streaks and "main vein" of ore must oc- 

 cupy nearly the same position originally occvipied by the more ferrugin- 

 ous strata after they had got their dip and strike. See fig. 40. 



The ore is taken out with the clay, and hauled up an incline, by means 

 of a stationary steam engine at its head, and dumped into a large wash- 

 ing machine, with revolving screens ; whence after the flints and sand 

 stones have been picked out, it is carried on an ironed tramway, to the 

 bridge house of the Furnace. See fig. 43. 



The ore forms from 10 to 50 per cent, of the mass excavated, and the 

 small amount of handling makes the ore cheap. 



The floor of the excavation is about sixty (60) feet below the level of 

 the wash machine. 



Shafts sunk from 30 to 35 feet deeper, in the floor, to a permanent 

 water level, have shown that other and even better ore deposits underlie 

 the workings, covered by the slanting undecomposed lime rocks. This 

 is an additional demonstration of the correctness of the theory above 

 stated. 



The upper ores will furnish stock for yet many years. After that, or in 

 case more furnaces be erected, or distant markets call for the shipment 

 of ore by railway, deep shafts or bore holes must be sunk to drain the un- 

 derground, and the lower ores may then be lifted to an extent which can 

 hardly be estimated now. 



The prism of ore in sight, technically speaking, if calculated roughly 

 from the areas exposed by the old and new open cuts, and by shafts sunk 

 at various times and in various parts of the floor, gives several millions 

 of wash-ore, lump-ore and pipe or rock ore. Thus taking the area exposed 

 at say 550 X 450 yards, and the depth at only 15 yards, we have 3,612,500 

 cubic yards, which on washing would yield 602,000 tons of prepared ore. 



