112 



GRAVITATIONAL METHODS 



[Chap. 7 



7-19). On top is a photo cell arrangement for the transmission of the 

 pendulum oscillations. 



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\ 



U. S. Coast and Geodetic Survey 



Fig. 7-19. Brown gravity apparatus. Upper part contains recording device and 

 photoelectric cell; lower (evacuated) part contains the (J ni, invar) pendulum. 



The Lcjay-Holweck pendulum apparatus is distinguished from other 

 pendulum instruments by its small size and weight. The pendulum is 



