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Method No. 3. 



The third method is not as accurate as either of the first two, but 

 much more rapid, and can be carried on with less expense, as the plane 

 table and operator are eliminated. With care accurate results can be 

 accomplished with this method. 



If a geologist is sent into a field to do a rapid piece of work and 

 time available for doing the work or character of the work would not 

 pay to employ the use of plane table and stadia this method is the 

 most satisfactory one to use. The reader must keep in mind that the 

 element of time is important to the oil geologist. He must finish his 

 work and get report to the chief geologist to pass upon, before another 

 company has an opportunity to obtain lease on valuable acreage that 

 he is likely to report favorable. 



In this method a barograph can be used to an advantage in con- 

 nection with the ordinary aneroid barometer. Set the barograph at 

 some place near center of area to be worked and proceed with aneroid 

 barometer as in Method No. 2, noting time all readings are made. At 

 night, instead of plotting curve as before, use curve of barograph and 

 proceed in same way to make correction for elevations. 



If a barograph is not available use two aneroid barometers, one 

 to be stationary and the other carried by geologist. In case two aneroids 

 are used the one stationary should be read every 15 or 20 minutes 

 throughout the day and a curve plotted from these readings. Proceed 

 as before in making corrections for elevations. 



Method No. 4. 



The fourth method can be used in case it is desirable to detail a 

 small area and neither a plane table, barograph or extra aneroid 

 barometer is available and time is short for completing the work. 



The geologist vises his aneroid to establish his own bench marks. 

 An elevation at a certain point may be assumed. Set aneroid at this 

 assumed elevation, noting the time. Drive in a circle making readings 

 at points where bench marks are desired, noting time of readings. Re- 

 turn to starting point within 45 minutes or an hour from time of start. 

 Repeat circuit, checking previous readings. Now these points can be 

 used as bench marks, making circuits from these points establishing 



