Bowie — Recent Gravity Work in the United States. 109 



The first column of the table for zone E gives the mean 

 elevation of the compartment in fathoms or feet, the second 

 the correction for topography and its compensation, assuming 

 the station to be at the same elevation as the compartment, the 

 third to seventh columns give a correction to the values in col- 

 umn 2 due to the elevation of the station above the compart- 

 ment, and the last five columns the correction to the quantities 

 in the second column should the station be below the mean 

 elevation of the compartment. The tables for the other lettered 

 zones are practically the same in form as those for zones E and 

 K, while the tables for the numbered zones are materially dif- 

 ferent owing to the absence of any correction for elevation of 

 the station above or below the compartments, and due also to 

 the fact that they are computed by a different formula. 



The following table gives the values for the separate zones 

 for six typical stations : 



Correction for Topography and Isostatic Compensation — Separate Zones. 





Kansas 



Pike's 



Colorado 



Grand 



Beau- 



San 





City. 



Peak. 



Springs. 



Junction. 



fort. 



Francisc 



Zone 



No. 39 



No. 43 



No. 42 



No. 46 



No. 18 



No. 54 



A 



+ 2 



+ 2 



+ 2 



+ 2 



+ 1 



+ 'a 



B 



+ 64 



+ 72 



+ 68 



+ 68 







+48 



C 



+97 



+157 



+160 



+160 







+35 



D 



+ 72 



+ 310 



+ 306 



+282 







+15 



E 



+30 



+ 540 



+408 



+ 336 







+ 1 



F 



+16 



+602 



+ 331 



+239 











G 







+512 



+192 



+ 120 











H 







+443 



+127 



+ 66 











I 







+412 



+ 78 



+ 33 











J 



-16 



+201 



- 11 



- 7 







- 2 



K 



-20 



+ 79 



- 71 



- 65 







- 1 



L 



-24 



- 32 



-147 



-132 







- 7 



M 



-53 



-290 



-369 



-391 







-14 



N 



-47 



-334 



-342 



-374 



+ 4 



+15 







-55 



—329 



-339 



-349 



+45 



+ 99 



18 



-10 



- 68 



- 68 



- 74 



+14 



+ 24 



17 



-10 



- 68 



- 69 



- 73 



+ 16 



+21 



16 



-10 



- 68 



- 69 



- 72 



+ 20 



+20 



15 



-11 



- 64 



- 68 



- 66 



+ 27 



+ 19 



14 



-11 



- 59 



- 62 



- 65 



+34 



+ 17 



13 



-20 



- 83 



- 81 



-101 



+ 52 



+25 



32 



-13 



- 48 



- 48 



- 55 



+ 36 



+23 



11 



-14 



- 30 



- 30 



- 34 



+ 29 



+21 



10 



-14 



- 17 



- 17 



- 15 



+ 19 



+14 



9 



- 8 











+ 3 



+ 14 



+10 



8 



- 1 



+ 9 



+ 9 



+ 11 



+ 14 



+15 



