136 
The American Geologist. 
Marcli, 1001. 
20 40 CO so 100 IZO 140 l«0 ISO 
FIG. 6. — steiniiauser's map, showing variation in attrac- 
tion OF gravity, as indicated by length of the second- 
beating PENDULUM. O = LENGTH IN EQUATORIAL BELT; 
I-5 = N0S. OF millimetres by which a PENDULUM HAS TO 
ue lengthened in order to beat seconds at different 
latitii)I-:s. 
copy of Sloinhauser's map, in which the variation of gravity is 
illustrated Ijy showing how many millimetres have to be added 
to the length of the pendulum which beats seconds at the equa- 
tor, to malce it vi])rate at the same rate elsewhere. In both 
northern and southern hemispheres the second-beating pendu- 
lum has to be steadily lengthened as we approach the poles, but 
the deviation is at a different rate for the two hemispheres. 
The surface of the southern hemisphere does not approach the 
earth's centre of mass at the same rate as the northern hemis- 
phere. If the earth's centre of mass is at its geometrical 
centre, then the earth's form is elongated southward like a peg- 
top. It is often held that the earth's centre of mass is to the 
south of its center of form, because of the accumulation of 
water in the southern hemisphere. It is held that the water is 
piled up there, owing to the greater density of the southern 
I 
