Bowie — Recent Gravity Work in the United States. 107 



Designation 

 of zone 



Inner radius 

 of zone. 

 Meters 



Outer radius 



of zone. Number of 

 Meters compartments 



A 













2 





1 



B 





2 







68 





4 



C 





68 







230 





4 



D 





230 







590 





6 



E 





590 







1280 





8 



F 





1280 







2290 





10 



G 





2290 







3520 





12 



H 





3520 







5240 





16 



I 





5240 







8440 





20 



J... 





8440 





12400 





16 



K 





12400 





18800 





20 



L. 





18800 





28800 





24 



M 





28800 





58800 





14 



N 





58800 





99000 





16 









99000 





166700 





28 





Degrees, minutes 

 and seconds 



Degrees, minutes 

 and seconds 



18 



1° 



29' 



58" 



l c 



41' 



13" 



1 



17 



1 



41 



13 



1 



54 



52 



1 



16 



1 



54 



52 



2 



11 



53 



1 



15 



2 



11 



53 



2 



33 



46 



1 



14 



2 



33 



46 



3 



03 



05 



1 



13 



3 



03 



05 



4 



19 



13 



16 



12 



4 



19 



13 



5 



46 



34 



10 



11.. 



5 



46 



34 



7 



51 



30 



8 



10 



7 



51 



30 



10 



44 



00 



6 



9 



10 



44 



00 



14 



09 



00 



4 



8 



14 



09 

 41 

 41 



00 

 00 

 00 



20 

 26 

 35 



41 

 41 



58 



00 

 00 

 00 



4 





20 



2 



6 



26 



18 



5. 



35 



58 



00 



51 



04 



00 



16 



4 



51 



04 



00 



72 



13 



00 



12 



3 



.... 72' 



13 



00 



105 



48 



00 



10 



2.. 



105 



48 



00 



150 



56 



00 



6 



1 



150 



56 



00 



180 



00 



00 



1 



It was found most convenient, in making the computations, 

 to have the radii of some zones in meters and others in degrees 

 and minutes of a great circle. All of the zones combined 

 together cover the earth completely. For each zone a special 

 reduction table was prepared, giving the relation between the 

 mean elevation of each compartment of that zone, and the 

 effect of the topography and compensation in that compart- 

 ment upon the intensity of gravitation at the station. The 

 mechanical part of the computation was performed by the use 



