AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 41 



finished model is then pasted up at the sides giving the 

 borehole as one edge of a distorted prism (Fig. 196). 



Lesser Deflection Records for Short Holes and Small 

 Deviations : The Plumbing Basket. — This method employed 

 in plumbing holes which have not deflected more than 



CSI r:|- vD CO 



(a) (6) 



Fig. 19a and b. — The Sperry-Sun Well Surveying Co.'s model. 



the borehole width, is often resorted to, since it is rapid 

 and cheap. It was evolved by the Parisian firm Entreprise 

 generate de fongage de putts etudes et traveaux de mines ^ 

 It is much appreciated in surveying freezing shaft holes and 

 prospect holes. It^ consists of a receptacle or basket filled 

 with lead and let down into the hole on a hawser. The 

 basket A (Fig. 20) is slightly less in diameter than the hole. 



^ Cavallier and Daxibine, Annates des mines, Paris, 1900. Series 9, 

 Vol. 18, p. 392; Kohler, Bergbaukunde, Vol. 6, p. 634; Berg und Hutt. 

 Ztg., p. 276, 1901. 



2 Schmidt, Trans. Inst. Mining Eng., Vol. 52, No. 2, p. 178, 1917; 

 Erlinghagen, Gluckauf, p. 705, June 8, 1907. 



