36 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



with side springs of steel as at G. For the bottom index 

 glass is used. Glass being wet by alcohol the index 

 retreats with it owing to capillarity and on rise of tempera- 

 ture the alcohol flows past it without moving it, the spring 

 also holding it; thus we get the minimum reading E. 



The upper index may be of iron, since alcohol does not 

 wet iron, so that on rise of temperature the iron is pushed 

 up and remains there when the column falls, showing the 

 maximum temperature F. Otherwise the spring glass 

 index is used. These can afterward be reset by a small 

 magnet acting on the springs. Full accounts of up-to-date 

 thermal survey methods can be obtained elsewhere.^ 



Length Recorder for Use When Inspecting Ropes. — 

 This device 2 is now employed for hoist ropes, and lowering 



Fig. 16. — Elevation. 



Fig. 16a.— Plan. 



ropes for valuable apparatuses and is used to enable a rope 

 inspector to find the position of broken wires or worn or 

 distorted places accurately to within a few inches. In 

 Figs. 16 and 16a a measuring wheel a, grooved to suit the 

 diameter of the rope d, is kept in driving contact with the 



1 Van Orstrand, C. E., Apparatus for the Measurement of Temperatures 

 in Deep Wells by Means of Maximum Thermometers, Econ. Geol., Vol. 19, 

 pp. 229-248, 1924. 



McCuTCHiN, J. A., Bull. Amer. Assoc. Petroleum Geol., Vol. 14, No. 5, 

 p. 536, May, 1930. 



Seifert, C, Fortschritte Mineral, Bd. 14, Part 2, pp. 167-291, 1930, for 

 notes on geological thermometers and bibliography. 



^ The firm of Reinhard Wagner, Bergwerksdarf Oberhausen (Rhld), 

 Germany; see also Gluckauf, Dec. 10, 1929. 



