ELECTRICAL METHODS 637 



2.190.322 Issued Feb. 13, 1940. Gennady Potapenko. "Method of Geophysical 

 Prospecting. 



2.190.323 Issued Feb. 13, 1940. Gennady Potapenko and D. Folland. "Method and 

 Apparatus for Geophysical Prospecting." 



2.190.324 Issued Feb. 13, 1940. Glen Peterson. "Method of Geophysical Prospecting." 

 2,200,096 Issued May 7, 1940. E. E. Rosaire and S. S. West. "Geophysical Explora- 

 tion by Time- Variant Electric Currents." 



2,201,256 Issued May 21, 1940. W. M. Barret. "Electrical Apparatus and Method 

 for Locating Minerals." 



2,202,369 Issued May 28, 1940.^ L. W. Blau and L. Statham. "Electrical Earth 

 Transients in Geophysical Prospecting." 



2,203,729 Issued June 11, 1940. J. J.Jakosky and P. B. Lyons. "Method and Ap- 

 paratus for Use in Determining the Geologic Nature and Characteristics 

 of a Formation Traversed by a Borehole." 



2,204,436 Issued June 11, 1940. D. S. Muzzey, Jr. "Commutation System." 



2,207,060 Issued July 9, 1940. J. J. Jakosky. "Method and Apparatus for Electrical 

 Exploration of the Subsurface." 



2,230,803 Issued Feb. 4, 1941. P. W. Klipsch, S. S. West, S. Bilinsky, and W. G. 

 McLarry. "Wave Synthesizing Network." 



2,231,013 Issued Feb. 11, 1941. P. W. Klipsch and S. S. West. "Electrical Prospect- 

 ing with Alternating Current." 



2,231,048 Issued Feb. 11, 1941. C. C. Beacham. "Process or Method of Geophysical 

 Prospecting." 



2,234,956 Issued Mar. 18. 1941. S. Bilinsky. "Exploration with Electrical Impulses." 



2,241,623 Issued May 13, 1941. D. Silverman and P. F. Hawley. "Electrical Sur- 

 veying." 



2,249,328 Issued July 15, 1941. E. E. Rosaire. "Calibration Means." 



2,250,703 Issued July 29, 1941. W. J. Crites and W. C. Rodgers. "Apparatus for 

 Locating Casing Seats." 



Re 21914 Issued Sept. 30, 1941. D. S. Muzzey, Jr., "Communication System." 



2.270.325 Issued Jan. 20, 1942. N. W. Matthews. "Auxiliary Electrode for Ground 

 Resistance Measurement." 



2,274,903 Issued Mar. 3, 1942. S. Krasnow and J. M. S. Kaufman. "Electrical Pros- 

 pecting Apparatus." 



2,276,974 Issued Mar. 17, 1942. G. M. Howard. "Method of and Means for Deter- 

 mining the Velocity of Propagation of Waves through Subsurface For- 

 mations." 



2,288,310 Issued June 30, 1942. T. Zuschlag. "Apparatus for Geoelectric and Seismic 

 Investigations." 



2,314,597 Issued Mar. 23, 1943. S. R. Phelan. "Methods of Making Geophysical 

 Surveys." 



2,314,874 Issued Mar. 30, 1943. H. M. Evjen. "Reversing Switch." 



2,335,024 Issued Nov. 23, 1943. J. M. Pearson. "Method and Apparatus for Making 

 Corrosion Studies." 



2,337,352 Issued Dec. 21, 1943. C. B. Sitterson, Jr., and T. M. Berry. "Metal 

 Detector." 



2,337,962 Issued Dec. 28, 1943. J. F. Atkinson. "Method and Apparatus for Deter- 

 mining Resistance of Ground Connections." 



2,342,627 Issued Feb. 29, 1944. K. H. Evjen and H. M. Evjen. "Apparatus for Mak- 

 ing Geophysical Explorations." 



2,342,628-2,342,629 Issued Feb. 29, 1944. H. M. Evjen and W. B. Lewis. "Coupling 

 Circuit." 



2,343,140 H. M. Evjen. 



2,344,672 H. Blasier. 



2,345,608 F.W.Lee. 



2,351,201 R. Gillis. 



2,354,535 G. Muffly. 



2,362,372 Issued Nov. 7, 1944. E. S. Halfmann. "Apparatus for Measuring Alternat- 

 ing Current in the Conductors and/or in the Sheaths of Electric Cables." 



2,375,022 Issued May 1, 1945. G. V. Morris and R. Adler. "Instrument for Testing 

 Ground Resistance." 



2,375,775-2,375,777, inc. Issued May 15, 1945. H. M. Evjen. "Electrical Prospecting 

 System." 



