Discussion. 



Professor I. C. White: I can add but little to the admirable presenta- 

 tion by Professor Orton. My studies in the Pittsburgh region have long ago 

 confirmed the absolute proof which Professor Orton has just given us. I 

 stated as early as 1886, in an article on this subject, that in my view it was 

 due to artesian pressure. This idea was also adopted by Mr. Westiugliouse, 

 president of the largest gas company in the world, the one which supplies 

 Pittsburgh with natural gas. But siugularly enough, although president 

 of this great organization, and having this idea in his miud in regard to the 

 origin of the pressure of gas, his company made no attempt to shut in any 

 wells until 1887, simply because the superintendents were afraid that the 

 pressure developed when the wells were closed would blow up the casing. 

 Finally, when the subject of the great waste of natural gas was agitated in 

 the papers and in the legislature, the superintendent of the field operations 

 undertook to shut in a well. He piled around a derrick several tons of 

 stone, cemented it together, and prepared for a pressure of something like 

 two or three thousand pounds to the square inch. To his great surprise, the 

 pressure gradually went up to only 500 pounds. After that they very soon 

 shut in every well they had. 



Now, although the rock that produces the gas in that region is a sand 

 instead of dolomitic limestone, as in Ohio, yet there is no reason to doubt 

 that it would show the same results Professor Orton has demonstrated. All 

 the data that I have collected goes to prove this statement. There is an in- 

 crease of pressure with the depth of the wells. The largest pressure that I 

 know of is 1,000 pounds to the square inch. This is in the valley of the 

 Ohio near Pittsburgh, and it took the well several hours to attain that press- 

 ure ; the depth was about 2,200 feet, and when proper calculations are 

 made from the point where that rock emerges from the Conemaugh river, 

 the pressure is sufficiently accounted for on artesian principles. The wells 

 in the Murraysville district are surrounded by what is called soda water, 

 which has the character of a bittern. It is not very salt, and some people 

 drink it as a mineral water ; but its specific gravity is very high. The first 

 well struck in Murraysville was allowed to play into the air for six years, 

 discharging 20,000,000 feet of gas daily, before any attempt was made to 

 utilize it; so that the original pressure of that field was probably never ob- 

 tained. The most reliable estimate ever made places it between 600 and 

 700 pounds to the square inch, which would be about what it should be 

 according to these calculations of artesian pressure. 



The largest well I have ever known in the Pittsburgh region is one that 

 developed a pressure of 800 pounds in a minute. That well was sold lor 

 $100,000. This will give you some idea of the value of the gas, which, as 



XIII— Bull. Geol. Soc. Am., Vol. 1, 1889. 



