304 



JOSEPH BARRELL 



tions. In Table XXI the attracting mass is supposed to have the 

 form of a vertical cylinder. With a given anomaly the deficiency 



TABLE XXI 



Vertical Cylinders Giving a Negative Gravity Anomaly of o.ioo Dyne at 

 Center of Top Surface of Cylinder 



Diameter 



Depth 



Density 



2.80— Density 



Thickness of cylinder of same 

 area and mass, but density 

 2.67 



Anomaly per 100 feet of mass 

 of density 2.67 expanded 

 to depth of cylinder as 

 given in second line 



76.8 km. 

 9.15 km. 

 - 0.31 

 2.49 



1,080 m. 

 3,550 ft. 



0.0028 dyne 



51 . 2 km. 

 30.5 km. 

 • 0.15 

 2.65 



1,700 m. 

 5,600 ft. 



0.0018 dyne 



102.4 km. 



61 .0 km. 

 — 0.07 

 2.73 



1,700 m. 



5,600 ft. 



0.0018 dyne 



51.2 km. 

 61 .0 km. 

 — 0.12 

 2.68 



2,770 m. 

 9,080 ft. 



o.ooii dyne 



TABLE XXII 



Spheres Giving a Negative Gravity Anomaly of o.ioo Dyne at Point Verti- 

 cally ABOVE ON THE SURFACE OF THE EaRTH 



Diameter 



Depth to center 



Density 



2.80 — Density 



Length of polar axis of oblate 

 spheroid of same equa- 

 torial section and same 

 mass, but density 2.67... 



Anomaly per 100 feet of 

 polar axis of mass at den 

 sity 2.67 if expanded to 

 diameter of sphere. . . . 



50. km. 

 25. km. 

 - 0.144 

 2.66 



2,700 m. 

 8,850 ft. 



O.OOII dyne 



100. km. 

 50. km. 

 — 0.072 

 2-73 



2,700 m. 

 8,850 ft. 



O.OOII dyne 



50. km. 

 32. km. 

 - 0.236 

 2.56 



4,420 m. 

 14,500 ft. 



0.0007 dyne 



100. km. 

 64. km. 

 - 0.118 



4,420 m. 

 14,500 ft. 



0.0007 dyne 



of mass will be least if the cyhnder extends from the station down- 

 ward instead of being at a greater depth. Furthermore, for a 

 given volume and density of cyhnder the gravitative force will 

 vary according to the ratio of the depth to the diameter. 



Let H = depth 



Let 2i?= diameter 



Let F = gravitative force 



