ELECTRICAL METHODS 633 



1,507,017 Issued Sept. 2, 1924. Lee de Forest. "Wireless Telegraph and Telephone 



System." 

 1,526,391 Issued Feb. 17, 1925. Edward S. Stewart. "Testing Apparatus." 

 1,573,337 Issued Feb. 16, 1926. Harold J. Vennes. "Electrical Bridge." 

 1,537,360 Issued May 12, 1925. H. T. F. Lundberg and H. J. J. Nathorst. "Ore 



Detector." 

 1,545,672 Issued July 14, 1925. Charles D. McArthur. "Static Discharger for Auto- 

 mobile Trucks." 

 1,553,742 Issued Sept. 15, 1925. Oscar R. Blatter. "Storage Battery." 

 1,564,940 Issued Dec. 8, 1925. Frank Spencer Chapman. "Method of Detecting the 



Presence and Approximate Location of Metallic Masses." 

 1,569,325 Issued Jan. 12, 1926. August Leib. "Radio Direction Finder." 

 1,585,591 Issued May 18, 1926. Heinrich Lowy. "Means for Electric Proof of the 



Distance of Electrically Conductive Bodies." 

 1,596,942 Issued Aug. 24, 1926. Harry Nyquist and Harry A. Etheridge, Jr. "Meas- 

 uring Transmission Phase Shift." 

 1,645,618 Issued Oct. 18, 1927. Harry Nyquist. "Method and Apparatus for Meas- 

 uring Transmission Delay." 

 1,647,236 Issued Nov. 1, 1927. Maurice B. Long. "Electrical Testing System." 

 1,652,227 Issued Dec. 13, 1927. Theodor Zuschlag. "Method of Investigating the 



Nature of Subterranean Strata." 

 1,660,405 Issued Feb. 28, 1928. Herman A. Affel. "High-Frequency Measuring 



System." 

 1,660,774 Issued Feb. 28, 1928. M. Vos and K. Sundberg. "Method for Electrical 



Searching of Ore." 

 1,665,662 Issued Apr. 10, 1928. Cecil E. Godkin. "Electromagnetic Detecting Device." 

 1,669,400 Issued May 8, 1928. Charles E. Vawter. "Impedance Meter." 

 1,672,328 Issued June 5, 1928. William A. Loth. "Method of Electromagnetic Under- 

 ground Prospecting." 

 1,673,249 Issued June 12, 1928. F._ A. Kolster. "Loop Antenna." 

 1,676,779 Issued July 10, 1928. Shirl Herr. "Device for Underground Prospecting." 

 1,676,847 Issued July 10, 1928. Theodor Zuschlag. "Method and Apparatus for 



Exploring Subterranean Strata." 

 1,678,489 Issued July 24, 1928. Karl Sundberg. "Method and Device for Detecting 



and Locating Ores in an Electromagnetic Way." 

 1,679,095 Issued July 31, 1928. Greenleaf Whittier Pickard. "Closed Tuned Coil 



of Loop Aerial." 

 1,679,339 Issued July 31, 1928. Shirl Herr. "Hidden-Metal Detector." 

 1,684,397 Issued Sept. 18, 1928. Francis A. Hubbard. "Electrical Testing." 

 1,692,530 Issued Nov. 20, 1928. Theodor Zuschlag. "Method and Apparatus for 



Locating Ore Bodies." 

 1,692,849 Issued Nov. 27, 1928. Max Mason. "Method of Determining the Nature 



of Subsoil." 

 1,695,032 Issued Dec. 11, 1928. William J. Shackelton. "Impedance-Measuring 



Bridge." 

 1,705,561 Issued Mar. 19, 1929. Paul G. Edwards and Harold W. Herrington. 



"Electrical Testing System." 

 1,708,386 Issued Apr. 9, 1929. Norbert Gella. "Electrical Prospecting Device." 

 1,718,352 Issued June 25, 1929. Edward H. Guilford. "Method of Locating Under- 

 ground Conductive Bodies." 

 1,718,497 Issued June 25, 1929. Byron W. St. Clair. "Telemetric System." 

 1,719,786 Issued July 2, 1929. Conrad Schlumberger. "Method for the Location of 



Oil-Bearing Formation." 

 1,724,794 Issued Aug. 13, 1929. W. W. Davis. "Method of Detecting Ore Deposits." 

 1,727,388 Issued Sept. 10, 1929. Herman A. Affel. "High-Frequency Measuring 



System." 

 1,732,311 Issued Oct. 22, 1929. Harry Nyquist. "Method and Apparatus for Testing 



Networks." 

 1,733,585 Issued Oct. 29, 1929. Joseph W. Dehn. "Method of Testing and Test Set." 

 1,743,386 Issued Jan. 14, 1930. Christian Paulson. "Electrical Testing Apparatus." 

 1,744,566 Issued Jan. 21, 1930. Everett V. Mott, Lewis H. Rovere and David H. 

 Rowland. "Ground Resistance Test Set." 



