474 



NEW YORK STATE MUSEUM 



then have been 1347 feet, which equals 641 pounds. The gage- 

 by which the pressure was tested was graduated only to 600 

 pounds, but the index traveled beyond this point and the figure 

 at the time was reported as 650 pounds. These facts may be 

 stated in tabular form. 



LOCATION Hf£?l below sea Tl^f,!'? Observed pressure 



to gas level pressure 



Muncie, Ind 900 ft ft 2S6 lb. 280-300 lb: 



Marion, Ind 870 78 323 323 



St Henry, 1L56 200 385 375 



Upper Sandusky, O... 1280 478 513 • 515 



Tiffin, O ' 1500 747 6U 650 



These are the best examples found that bear on this point, 

 but the mind must be peculiarly constituted that can consider 

 these facts as accidents. 



The Kingsville gas field of Ontario is another case in point. 

 It finds its supply in a very pure and porous dolomite of Silurian 

 (Upper Silurian) age, and the pressure of all the wells drilled, 

 30 or more in number, is approximately the same, viz, 400 pounds. 

 Where the gas is withdrawn by a pipe line, the pressure falls 

 equally in all contiguous wells, whether connected with the line 

 or not. The hight to which the salt water rises has not been 

 fully determined as yet, but the highest pressure noted, namely 

 415 pounds, would show a water column of 850 feet, if the specific 

 gravity of the salt water found proves to be the same as that in 

 the porous Trenton of Ohio. As the wells are drilled about 1025 

 feet to the gas vein and as the elevation of the surface is approx- 

 imately 600 feet above tide, the salt water should be found 

 to rise to within 175 feet of the surface. If this is hereafter 

 found to be the case, it will complete the demonstration in the 

 most conclusive manner. It is to be noted that observations 

 will be valid only in wells that are cased below 500 feet, as a 

 fresh water vein of great force is reached at about this depth. 



There are two distinct forces, then, that take part in the rock 

 pressure of natural gas, viz, its expansive power, and the weight 

 of the salt water column that compresses it. The first cause may 

 exceed the second, and in such cases it would completely mask 

 the latter. Where no porous rocks are found and where a water 

 column is therefore wanting, we are obliged to rely altogether on 



