28*2 I. C. WHITE DEEP WELL NEAR MCDONALD, PENNSYLVANIA 



beds at this interesting locality, so far removed from any exposure of 

 these rocks, the nearest Oriskany outcrops being at Altoona, Pennsyl- 

 vania, and Keyser, West Virginia, each of which is nearly 100 miles dis- 

 tant and in the heart of the Alleghany Mountains. 



The great reduction in temperatures found at 6,000 feet is due to the 

 sudden expansion of natural gas, a small now of which under great pres- 

 sure (probably 2,500 pounds or more to the square inch) was encoun- 

 tered near and below that horizon. The temperature of 156° Fahrenheit, 

 recorded first at 6,095 feet, is, however, so much greater (156° to 140°), 

 namely, 16°, than that (140°) recorded at 5,800 feet that it probably 

 was elevated a few degrees by the pounding of the drill on the hard sand- 

 stone, and this looks all the more probable, since the water found at 6,250 

 feet has only the same temperature (156°), which itself reveals a rapid 

 increase in gradient below 5,800 feet, or at the rate of 1 degree for every 

 29 feet. The results of other temperature measurements on this well at 

 greater depths will prove of surpassing interest. 



