Mattison, Hiram, 1811-1868 · New York, Huntington and Savage, Mason and Law · leaf 34
es. [1. These hemispheres are distinguished as upperand lower with reference to the observer only. 2. The sensible horizon is half the diameter of theearth, or about 4000 miles from the rational: andyet so distant are the stars that both these planesseem to cut the celestial arch at the same… … 112. What are the Zenith and Nadir Points ?The Zenith is the point directly overhead, and theNadir the point directly under our feet. [1. These directions, it must be remembered, are merely relative. As the earth is asphere, inhabited on all sides, the Zenith point is merely opposite its center,…
Astronomy
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