These were represented on the globe, first by Mercator, by greater or lesser circles or “winding lines,” and were intended to be of aid to seamen in navigating from port to port across the great oceans. In their representation on the globe map cognizance was taken of the fact that all meridians of all places pass through both poles, crossing the equator therefore at right angles and all other circles parallel to it, and that if the navigator’s course is in any other direction than toward one of the poles he is continually changing his horizon and his meridian. The rhumbs as drawn were made to cut all meridians of all places at equal angles and to respect the same quarters of the world, that is, direction, whatever the horizon. Rhumbs can represent great circles only when they coincide with the equator or with any meridian.[202] In the matter of draughting, printing, and mounting celestial globe gore maps the method employed may in general be said to be identical with that followed in terrestrial globe construction. It should, however, be noted that in pasting the gores on the surface of the sphere they were often so applied as to have their points or angles meet at the pole of the ecliptic, in what may be called the ecliptic system, instead of applying them to meet at the poles of the equator, the globe itself being generally so mounted as to revolve in the equatorial system, its poles of revolution being attached to the meridian circle.[203] The figures of the several constellations were usually drawn with care, occasionally with high artistic taste, as those drawn by Hevelius (Fig. 137) and copied by Gerhard and Leonhard Valk for their celestial globes (Fig. 138). The several stars represented on the map, the majority of them being either lettered or named, were usually from the first to the sixth magnitude, each represented in its proportional size, while an explanatory table for the several magnitudes was usually given on some one of the gores. The stars and the figures of the several constellations, let it be noted, were not made to appear on the surface of the sphere, with rare exceptions, in their relative location as they appear to the observer who beholds them from his position on the surface of the earth, but are reversed. To the astronomer the earth is but a point in space, to the layman, so far as mere appearance is concerned, it is the center about which the starry heavens appear to revolve. With the pole (north for us in the northern hemisphere) as the center of the dial face the stars appear to move in a direction the reverse of that in which the hands of a clock are made to move. The astronomer, that is, the celestial globe maker, thinks of himself as placed beyond the vaulted heavens in which the stars appear to be located, and as looking down upon this vaulted dome as on the surface of his celestial globe. An illustration may here well serve us. As one observes serves Ursa Major