Improvements in devices for giving a planar representation of the terrestrial globe

摘要

644,026. Maps. COKER, A. W. May 27, 1947, No. 14115. [Class 146 (ii)] A device for giving a planar representation of the terrestrial globe comprises a map movable past a mask having a circular orifice therein, the map representing the globe by a projection wherein the equator is shown by a straight line 2, latitude lines by equally-spaced lines 4 parallel to the equator, and the meridians by semi-circles 3 of the same radius as the aperture with their centres equally spaced along the equator, the map being positioned so that the equator line passes through the centre of the aperture. In one form, Fig. 1, the sheet on which the map is represented, is cut away along one extreme meridian 4a and at the other extreme meridian has a plain margin 5 which is secured by adhesive to the other end to form a continuous band. The band is stretched over spindles 7, Fig. 2, carried by partitions 11 in a shallow box-like casing with the circular aperture 17 in its upper face 16, the aperture diameter being approximately equal to half the length of the band. The partitions 11 are inclined to the box sides 10 at angle equal to the obliquity of the ecliptic. A representation 19 of a stand may be provided on the face 16. When the spindles 7 are rotated by knobs 14, the effect of a rotary globe is obtained. One of the spindles may be urged away from the other spindle by springs or each spindle may consist of a thin rod with sprocket wheels engaging perforations in the map edges. An aperture may also be provided in the lower face of the casing. In another form, Fig. 7, the map 22 has plain ends and is passed around a card 24 and the ends secured by adhesive, projections 25 on the card serving to retain it. A strip 27 is attached to the plain portions of the map and the whole is then placed in an openended envelope with a circular aperture as before so that the map can be pulled around the card and past the aperture by means of the ends of the strip 27. In this form, parts of the map at one end may be repeated at the other end. According to a modification, a map projection of a complete globe may be mounted on each side of a card which is slidable through an openended envelope with an aperture on each face. The maps are so positioned relatively to one another that the part exposed on one side is displaced 180 degrees from that on the other side.