44 NOETLING: PETROLEUM IN BURMA. 



has a temperature of 97 F., the temperature is never higher than 

 85 , but even this and the next lower temperature, 84 , are not com- 

 mon ; the bulk of the wells possess a temperature between 75 F. 

 and 82 F., that is to say the temperature is much lower than that 

 recorded in any of the pit wells of the Yenangyoung oil field. It 

 is therefore beyond doubt that the source of the mud volcanoes 

 must be close to the surface. 



The fact must also not be overlooked, that often wells which are 

 close to each other differ in temperature, though not greatly. 

 Much more important appears to me the probability that, owing to 

 the superficial position of the beds from which the mud and gas is 

 derived, the temperature changes with the season. This hypothesis 

 could easily be confirmed by a series of observations extending over 

 a few years. 



If the change of the temperature with the season cannot be abso- 

 lutely proved, for the present it is quite certain that the activity of 

 the mud wells changes with the season, or more accurately with the 

 level of the river. When the river is high, the mud volcanoes are 

 very active, when it is low, they subside into a comparative state of 

 rest. 



I first visited the mud volcanoes in February 1888 when they were 

 at a comparative state of rest, but in June 1888 when I revisited 

 Minbu they were all very active. The same applies to my visit in 

 May 1889, when they were all more or less active, while in March 

 1895, they were generally speaking less active. It seems to me 

 no mere accident that a greater activity should coincide with the 

 high level of the river during the rains or a state of comparative 

 rest with that of a low level during the dry season. Having already 

 mentioned that the source of the ejected mud cannot possibly be very 

 deep, it is probable that the change in the level of the ground water 

 which must happen with the rise and fall of the river, influences the 

 activity of the mud volcanoes. 



( 90 ) 



