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Book II chapter 13

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on the axis and magnetick poles.

l et the line be called the axis which is drawn in the earth (as in a terrella) through the centre to the poles. they are called πόλοι by the greeks from πολεῖν, to turn, and by the latins they are also called cardines or vertices; because the world rotates and is perpetually carried around them. we are about to show, indeed, that the earth and a terrella are turned about them by a magnetick influence. one of them in the earth, which looks towards the cynosure, is called boreal and arctic; the other one, opposite to this, is called austral and antarctic. nor do these also exist on the earth or on a terrella for the sake of the turning merely; but they are also limits of direction and position, both as respects destined districts of the world, and also for correct turnings among themselves.

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