934 EXPLORATION GEOPHYSICS 



2.266.040 Issued Dec. 16, 1941. H. Hoover, Jr. "Geophysical Prospecting Receptor 

 Circuits." 



2.266.041 Issued Dec. 16, 1941. H. Hoover, Jr. "Geoph3'sical Prospecting Receptor 

 Circuits." 



2,266,837 Issued Dec. 23, 1941. H. F. Wiley. "Method and Apparatus for Trans- 

 lating Seismic Waves." 

 2,267,357 Issued Dec. 23, 1941. O. F. Ritzmann. "Apparatus for and Method of 



Seismograph Recording." 

 2,267,858 Issued Dec. 30, 1941. C. H. Dix. "Method of Seismic Surveying." 

 2,268,130 Issued Dec. 30, 1941. M. M. Slotnick. "Method of Geophysical Investi- 

 gation." 

 2,269,453 Issued Jan. 13, 1942. E. L. Gayhart. "Device for Detecting Displacements." 

 2,269,890 Issued Jan. 13, 1942. L. W. Blau. "Seismic-Electric Prospecting." 

 2,271,864 Issued Feb. 3, 1942. P. M. Honnell and L. W. Dickerson. "Seismic Wave 



Detector." 

 2,272,201 Issued Feb. 10, 1942. H. Hoover, Jr. "Method and Apparatus for Signaling." 

 2,272,984 Issued Feb. 10, 1942. O. F. Ritzmann. "Seismograph." 

 2,276,306 Issued March 17, 1942. H. Hoover, Jr. and H. C. Schaeffer, "System for 



Making Weathering Corrections." 

 2,276,335 Issued March 17, 1942. R. A. Peterson. "Method of Making Weathering 



Corrections." 

 2,276,423 Issued March 17, 1942. D. Silverman. "Recording System." 

 2,276,565 Issued March 17, 1942. M. G. Crosby. "Limiting Amplifier." 



2.276.708 Issued March 17, 1942. R. D. Wyckoff. "Seismograph Amplifier." 



2.276.709 Issued March 17, 1942. R. D. Wyckoflf. "Apparatus for and Method of 

 Seismograph Prospecting." 



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

 mining the Velocity of Propagation of Waves through Sursurface For- 

 mations." 

 2,277,521 Issued March 24, 1942. M. D. McCarty. "Timing Device." 

 2,279,191 Issued April 7, 1942. J. L. Adler. "Method and Apparatus for Seismic 



Surveying." 

 2,281,949 Issued May 5, 1942. O. F. Ritzmann. "Apparatus for Seismograph Pros- 

 pecting." 

 2,283,200 Issued May 19, 1942. J. W. Flude. "Method and Apparatus for Subsurface 



Mining." 

 2,285,610 Issued June 9, 1942. O. S. Petty. "Method and Apparatus for Seismic 



Surveying." 

 2,286,106 Issued June 9, 1942. O. F. Ritzmann. "Apparatus for and Method of 



Receiving and Recording Vibrations." 

 2,286,170 Issued June 9, 1942. C. A. Heiland. "Selector System for Amplifiers." 

 2,286,386 Issued June 16, 1942. D. Silverman. "Seismometer." 

 2,286,567 Issued June 16, 1942. J. O. Parr, Jr. "Seismic Surveying." 

 2,291,779 Issued Aug. 4, 1942. W. R. Welty. "Geophysical Apparatus and Method." 

 2,294,627 Issued Sept. 1, 1942. J. O. Parr, Jr. "Seismic Surveying." 

 2,296,754 Issued Sept. 22, 1942. A. Wolf and L. G. Cowles. "Astatic Electromag- 

 netic Vibration Detector." 

 2,297,319 Issued Sept. 29, 1942. J. O. Parr, Jr. "Seismic Circuits." 

 2,298,020 Issued Oct. 6, 1942. J. O. Parr, Jr. "Seismic Surveying." 



2.301.739 Issued Nov. 10, 1942. J. P. Minton and E. M. Shook. "Gain Control for 

 Seismograph Amplifiers." 



2,302,219 Issued Nov. 17, 1942. G. W. Hostetler. "Infinite Period Seismometer." 



2.303.357 Issued Dec. 1, 1942. H. Hoover, Jr. "Seismic Wave Amplifier." 



2.303.358 Issued Dec. 1, 1942. H. Hoover, Jr . "Stable Seismic Wave Amplifier with 

 Automatic Volume Control." 



2,303,413 Issued Dec. 1, 1942. H. W. Washburn. "Seismometer." 



2,304,738 Issued Dec. 8, 1942. M. D. McCarty. "Seismograph." 



2.304.740 Issued Dec. 8, 1942. J. P. Minton. "Ai:ethod for Recording Seismic Waves." 

 2,304,901 Issued Dec. 15, 1942. J. D. Eisler. "Timing Device." 



2,305,383 Issued Dec. 15, 1942. _ H. Hoover, Jr., C. G. Morgan and N. J. Christie. 

 "Geophysical Exploration System." 



2,305,543 Issued Dec. 15, 1942. M. D. McCarty. "Expander for Electrical Seis- 

 mographs." 



