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"One standing at O will only see the half of the Sky which is above the circle NESW. The whole sky will seem to be turning about the line POP'; the Stars will seem to be moving along the paths EQW, BAB', etc. Stars so near the North Pole that they are inside the dark area KPN will never set."—The Foundation Library, 1911

The Sphere of the Sky

"One standing at O will only see the half of the Sky which is above the circle NESW. The whole sky will…