276 REPORTS ON THE STATE OF SCIENCE, ETC. 



(d) Presence of large bodies of cool water, adjacent to the strata. — This 

 factor serves to demonstrate the cooling effect of a large body of water (five 

 miles from the Lake Superior copper mines the gradient is i° F. per 95 ft. ; 

 close to the lake, only i° F. per 250 ft.). 



The author concludes that in any part where observations are taken there 

 are many conflicting factors which have to be considered, and the difficulties 

 attendant on arriving at any definite conclusions will be obvious. 



Description of Apparatus for the Measurement of Temperatures in 

 Deep Wells ; also, Some Suggestions in regard to the Operation 

 of the Apparatus, and Methods of Reduction and Verification 

 of the Observations. 



By C. E. van Orstrand. 

 American Petroleum Institute, Bulletin 205, 1930, pp. 9-18. 



In a brief introduction to the article van Orstrand says that of the various 

 methods that have been proposed for the measurement of temperature in 

 deep wells, two only, the electrical resistance thermometer method and the 

 mercury maximum thermometer method, have yielded results of sufficient 

 importance from the standpoint of efficiency and accuracy to justify their 

 use in making an extended temperature survey. 



These two methods are described in this article. 



The advantages of the electrical resistance thermometer method over the 

 mercury maximum thermometer method are, according to the author, so 

 great that it will undoubtedly come into general use as soon as the main 

 obstacles — the initial expense of the necessary equipment and the difficulty 

 of constructing leads that will remain intact after being immersed in a 

 mixture of crude oil and salt water — are overcome. 



The results of the tests carried out by this method are shown in a depth- 

 temperature curve of a deep well, E. T. Price No. 9, South Penn Oil Co. 

 From this figure the minute details of the temperature distribution are 

 put in evidence. A brief description of the apparatus is given. 



The mercury maximum thermometer method has the disadvantage of 

 being slow and tedious. Its chief advantages are minimum initial expense 

 and the certainty of obtaining an accuracy of rather less than o • 3° F., regard- 

 less of the fluid contents of the well. The two methods of handling maximum 

 thermometers : (1) by means of the bailer and (2) by means of a hand- 

 operated machine, are described. Thermometer holder and containers, as 

 well as other pieces of apparatus, and several views of the hand-operated 

 machine are given in a series of pictures. 



The second part of the article deals with some suggestions in regard to 

 the operation of the temperature apparatus : (a) Tests with the oil well 

 machinery, and (b) tests with a hand-operated machine. The operation is 

 explained and the elimination of the chief sources of error in handling the 

 thermometers is mentioned. 



The last chapter of the article deals with some suggestions in regard to 

 the correction and verification of the observed temperature data. The 

 possibility of accurate location of the isogeothermal surfaces owing to the 

 difficulty of obtaining a correct answer whether the well is in temperature 

 equilibrium or not is discussed. 



In conclusion the author makes statements in regard to the accuracy with 

 which the isogeothermal surfaces can be determined ; he says : ' That 

 they are smooth uniform surfaces before the drill penetrates the pay sands 



