Lesley.] QQ [April. 



from each square mile of eacli sandrock, in addition to that 

 above, amomiting to nearly 50,000 barrels of oil. This is 

 at the lowest calculation. In the case of a well yielding 

 one or more thousand barrels of oil per day, for a year or 

 years, we have only to imagine a single four- or five-inch fis- 

 sure crossing the upper and lower rocks to a height or depth 

 of one or two hundred feet, and extending a mile or two in 

 length, the oil contents of which will amount to millions of 

 barrels, apart from all side supplies. Along the line of one 

 such fissure, it is easy to see that a dozen first-class flowing 

 wells might last for several years. By ordinary wells it 

 would be practically inexhaustible. 



It is not upon these exceptional fissures that the future 

 * trade will rely ; but upon the myriads of cleavage-planes and 

 cross-cracks which break up the whole crust into cubes, so 

 far as it consists of sandrocks. The number of grand open 

 fissures must be very small ; the number of first-class flowing 

 wells is as yet extremely small, — one or two dozen out of five 

 or ten thousand wells in the Oil Creek region. I judge that 

 not more than one well in ten or twelve yields more than one 

 barrel of oil per day. The large majority of the wells must 

 necessarily depend for their supplies upon the slow circula- 

 tion of the mingled fluids, salt water and oil, forever going on, 

 exhausting and refreshing itself in the porous and cracked 

 body of the sandstone formations. But in this very fact we 

 have a guarantee for the genuineness of the area under dis- 

 cussion as an oil region, the certainty of obtaining petroleum 

 by boring, and the protracted continuance of the supply for 

 many years. All sand and gravel beds are mere sponges, 

 perpetually saturated with oil and water, the mingled fluid 

 being slowly driven towards every available outlet by the gas 

 which is generated with and from the oil. Such spongy rocks 

 must be enormous reservoirs of petroleum, which it is in fact 

 almost impossible for man to exhaust, as I have shown above. 

 The Canadian petroleum occupies a still lower horizon than 

 the Venango County petroleum, the distance between them in 

 New York and Pennsylvania being variously estimated at 

 from 2000 to 3000 feet. Its general relationship to the 



