248 



BOWIE: ISOSTASY IN INDIA 



TABLE 2 



STATION 



1. Bhopal. . . 



2. Balianpur 



3. Kina 



4. Goona. . . 



5. Lalitpur. 



6. Sipri 



7. Jhansi. . . , 



8. Gwalior. . 



9. Dholpur. 



10. Agra 



11. Muttra.. 



12. Hathras. . 



13. Aligarh.. 



14. Khurja. . 



7o 



978.835 

 978.892 

 978.896 

 978.928 

 978.931 

 978.983 

 978.984 

 979.039 

 979.073 

 979 . 107 

 979.128 

 979 . 139 

 979 . 160 

 979 . 186 



Qo-yo 

 (Free Air) 



+ 0.028 



+ 0.049 , 



+ 0.025 



+0.025 



-0.005 



+0.036 



+0.006 



-0.020 



-0.020 



-0.001 



-0.004 



-0.009 



-0.028 



-0.043 



go"-yo 



(Bouguer) 



g -y 



(Hayf ord ) 



0.029 

 -0.013 

 -0.022 

 -0.030 

 -0.047 

 -0.018 

 -0.024 

 -0.043 

 -0.040 

 -0.020 

 -0.024 

 -0.030 

 -0.049 

 -0.066 



+0.021 

 +0.038 

 +0.025 

 +0.018 

 -0.002 

 +0.027 

 +0.013 

 -0.008 

 -0.005 

 +0.017 

 +0.015 

 +0.011 

 -0.007 

 -0.019 



The means of the anomalies are as follows: Without regard to 

 sign: Free Air, 0.021; Bouguer, 0.032; Hayf ord, 0.016. With 

 regard to sign: Free Air, +0.003; Bouguer, -0.032; Hayf ord, 

 +0.010. 



This formula makes the mean Hayford anomalies without 

 regard to sign smaller than the mean anomalies by the other 

 methods, but the mean with regard to sign is smaller for the Free 

 Air anomalies. The sign of the Free Air anomalies seems to 

 change with the change in elevation of the stations. All except 

 one of the anomalies at stations above 800 feet are positive, 

 while all stations with elevations less than 800 feet have nega- 

 tive anomalies. The Bouguer anomalies are all negative, and 

 the values are double the values of the Hayford anomalies on 

 an average. 



With the 1901 Helmert formula applied the anomalies indicate 

 that the rigid crust postulated in the Bouguer method is far from 

 the truth. 



The United States Coast and Geodetic Survey formula' for 

 theoretical gravity (Helmert's formula of 1901 with a new first 



^ See p. 25, Effect of Topography and Isostatic Compensation upon the Inten- 

 sity of Gravity. Special Publication No. 12, U. S. Coast and Geodetic Survey. 



