SOMETHING ABOUT OIL. 283 



may be locally restricted, the impervious stratum must 

 present the form of a dome or roof. The underlying strata 

 may, and generally do, conform in position to the roofing 

 strata. We have here the requisite conditions for accumu- 

 lation. Some portion of the oil and gas may filter through 

 to the surface, or it may not. Obviously, if the outlet be 

 large, the product must escape as fast as elaborated. If 

 the reservoir be nearly closed, it may hold the products of 

 the slow distillation of thousands of years. When one of 

 these store-houses is exhausted it will be filled again, but 

 perhaps not before the millennium. 



I said that the oil and gas would displace the water pre- 

 viously occupying the spaces beneath the roof. It is plain 

 that these substances must be hard pressed by the sur- 

 rounding waters, re-enforced as they are on all sides by a 

 virtual column reaching to the surface of the earth, which 

 may be a hundred or five hundred feet above. The lateral 

 pressure of a column of water five hundred feet high is 

 enormous. All this the forming oil and gases must resist. 

 No wonder that when given vent from above they some- 

 times burst forth with tremendous violence. At a well 

 which I visited in Knox County, Ohio, the pressure of the 

 confined gas was 180 pounds to the square inch, in addition 

 to the pressure of a column of water 600 feet high. It es- 

 caped from the mouth with a roaring sound which could be 

 heard at the distance of a mile. The supply was sufficient 

 to illuminate a large city, and it continued to escape for 

 several months.* When conducted horizontally through 

 a pipe to the outside of the building and ignited, it formed 

 a ragged and spiteful stream of fire of the diameter of a 

 hogshead, which roared like a conflagration, and caused an 

 illumination which was seen at the distance of sixteen 



* This was in May, 1 8G6. A letter from Peter Neff, Esq. , of Gambier, 

 dated June, 1S438, states that this well is still ''blowing. 1 ' 



