426 



TABLE 567. 



ACCELERATION OF GRAVITY (0) IN THE UNITED STATES- 



The following table is abridged from one for 219 stations given on pp. 50 to 52, Special Publication No. 40, U. S. 



nirvey. The observed values depend on relative determinations and on adopted value of 980.112 



for Washington (Toast and C.etxlctic Survey Office, see footnote, Table 566). There are also given terms necessary 



in reducing the theoretical value (Table 565) to the proper elevation (free-air) and to allow for topography and isostatic 



compensation by the Hayford method (see introductory note to Table 566). 



To a certain extent, the greater the bulk of material below any station, the less its average density. This phenomenon 

 is knov. c compensation. The depth below sea-level to which this compensation extends is about 96 km. 



Below this depth any mass element is subject to equal (fluid) pressure from all directions. 



SMITHSONIAN TABLES. 



