ELECTRICAL METHODS 631 



seen in Figure 397. This indication was located during a high frequency 

 electromagnetic survey of a property in Des Meloizes Township, Quebec, 

 Canada. This indication was checked over a distance of 2000 feet between 

 drill hole No. 1 and No. 8, and it is reported that the drill holes cut a 

 wide zone of sulphide mineralization. The conductor is a dipping sheet 



1300' ■ 

 1200' 



MOO' ELEVATI0f4 Q q q o o o 



_suR£xct: 



> r " It ii — H — ^ — ij 



ooo-- 



800'- 



PROFILE 



SECTION 



^CONDUCTOR 

 SECTION DRAWN AT DRILL HOLE NO I 



Fig. 397. — Drill results on a shallow high frequency indication. 

 {A.I.M.E. Geophysical Prospecting, Tech. Pub. 134.) 



vein. The "axis" of the conductive zone was determined by use of the 

 correction curve. This axis lies close to the top of the conductor because 

 of the poor penetrating power of the high frequencies and also because 

 the near-surface flow of induced current has a much greater eflfect than 

 that flowing in the lower portions. 



ELECTRICAL METHODS 



UNITED STATES PATENTS* 



17,844 Frank S. Chapman. "Method of Detecting Presence and Approximate 



Location of Metallic Masses." 

 274,882 Issued Mar. 27, 1883. Fred H. Brown. "Apparatus for Detecting Mineral 



Ores." 

 277,087 Issued May 8, 1883. Cromwell F. Varley. "Electric Divining Rod." 

 293,518 Issued Feb. 12, 1884. Jerome Prince. "Means for Electrically Locating and 



Following Veins of Metal in the Earth." 

 308,908 Issued Dec. 9, 1884. August P. Lighthill. "Means for Electrically Locating 



Mineral Veins." 

 367,422 Issued Aug. 2, 1887. Lemuel Mellett. "Electrical Ore Detector." 

 367,541 Issued Aug. 2, 1887. Lemuel Mellett. "Electric Ore-Indicator." 

 380,842 Issued April 10, 1888. John R. Williamson and William W. Hickies. 



"Apparatus for Examining Ores." 

 412,924 Issued Oct. 15, 1889. Jesse F. Kester. "Electrical Metal Detector." 

 438,041 Issued Oct. 7, 1890. Robert L. Watkins. "Metal and Circuit Detector." 

 446,730 Issued Feb. 17, 1891. Fred Harvey Brown. "Induction Coil." 

 645,910 Issued Mar. 20, 1900. Fred Harvey Brown. "Process of Locating Metallic 



Minerals or Buried Treasures." 



* In addition to those mentioned in text. 



