SEISMIC METHODS 



645 



Fig. 401.- — Horizontal component variable reluctance seismometer. A, transducer; 

 B, inertia mass; C, frame; £, leveling screw; F, adjustments. (Courtesy of Hugo 

 Benioff, California Institute of Technology.) 



Fig. 402. — Short period galvanometer recorder. A, drum carrying photo- 

 graphic paper; B, short period galvanometer; C, synchronous motor drive; 

 D, control panel; E, leveling screw; F, lamp housing; G, helical screw for 

 transverse movement of drum. (Courtesy of Hugo Benioff, California Insti- 

 tute of Technology.) 



