| 摘要 |
This is a teaching apparatus intended, by easy manipulations, to explain various problems relating to the apparent relative movements of the earth, of the sun and of the moon. The apparatus comprises a fixed frame 1 supporting a plate 2 embodying the horizontal plane of the observation site, pierced by a circular hole in order to permit the passage of the movable part which comprises a flat ring 5 traversed by a shaft 6 embodying the axis of the world and that of the earth assumed to be immobile at the centre of the world 8. The trajectories of the moon and of the sun are embodied by rods on which the moon and the sun can be made to slide. By varying, as a function of the latitude of the observation site, the angle of the shaft 6 with the horizon and by making the ring 5 turn it is possible, after tests at different latitudes, to deduce the answers to the questions. It is possible, by adding a few accessories, to find the solution to several problems relating to the sky. <IMAGE>
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