Note 4 — Chapter I · GEOLOGY.
Reading edition
The compression of the earth is the flattening at the poles. Its numerical value is equal to the difference between the equatorial and polar diameters, expressed in feet or miles. [The amount of compression, oblateness at the poles, is measured by the ratio of the difference of the equatorial and polar diameters to the equatorial diameter, which is technically termed the oblateness. The following are the dimensions of the earth in miles:
Miles. Diameter.
Radius at the equator 3962·60 = 7925·2
Radius at the pole 3949·60 = 7899·2
Difference of equatorial and polar radii 0013·00 = 0026·0
Mean radius, or at 45° Latitude 3956·10 = 7912·2
Mean length of a degree 0069·05 ——
The fourth part of a meridian 6214·20 ——]