Improvements in devices for illustrating the apparent movements of the stars and planets

摘要

244,448. Zeiss, C. [Firm of]. Dec. 11, 1924, [Convention date]. Planetaria.-Apparatus for projecting images of the stars on a hemispherical screen comprises two groups of projection-devices carried on a support, each group consisting of a number of projectionappliances adapted to receive light from a source common to the respective group, the groups being arranged to project images of the whole fixed-star sky in such a way that the projection appears to be effected from a point midway between the groups. The apparatus is mounted on two bars a', a2, Figs. 1 and 2, suspended horizontally by ropes o1, o2, and held in position by other ropes o3, o'. Pivotally mounted in the bars is a body n in which a carrier b is carried to rotate about an axis X-X. A shaft d is mounted in the carrier b so that its axis Y-Y is at an angle of 23¢‹ to the axis X-X. The body n is rotated in the bars a', a2 until the axis X-X is at an inclination to the plane of the horizon equal to the latitude of the place at which the apparatus is used, an index n3 and scale a3 being provided for this purpose. A set-screw a0 serves to secure the apparatus in adjusted position. The carrier b is rotated by gear-wheels b1, c' from a motor c2 mounted on the body n. The shaft d is rotatable about the shaft Y-Y and is fixed in position by the set-screw (d0. Screwed to the ends of the shaft d are collars d10, d11 carrying plates d2a, d2b between which known devices for projecting the images of the sun, moon, Mercury, Venus, Mars, Jupiter and Saturn are mounted. To the outer of the plates d2a and d2b are fixed hemispherical casings carrying a number of projection-appliances d'a, d7b. Glow lamps d8a, d8b common to the respective projection-appliances and of which the filaments are on the axis Y-Y and enclose the centres of the casings, are provided, and the appliances are mounted so that images of the whole northern and southern fixed-star sky can be projected nn the screen. The images on the lantern plates are so marked that projection appears to come from the point of intersection E of the axes XX, Y-Y. Projection-appliances p1 - - p6 are mounted on the apparatus to project circles corresponding to the ecliptic, and other appliances q1 - - q4 are provided on the bar a' to project a circle corresponding to the meridian. As the appliances q1, q2 are in such a position that they are obscured by parts of the apparatus during rotation, further appliances q1a and q2a are provided on the bar a2 and are arranged so that the lines projected by the two sets of appliances coincide. The apparatus is so mounted that the point E is also the centre of gravity. In a modification the bars a1, a2 are supported on frames equidistant from the point E. The Specification as open to inspection under Sect. 91 3) (a) refers also to a modified arrangement, shown in Fig. 4 (Cancelled), for use when the supporting-means is so thick as to impede the projection. A bar j6, slideable in a guide e and rotatable in a holder j about an axis N-N parallel to the axis Y-Y, is provided with two projection-appliances j1a, j2a so arranged that the images projected on the screen overlap. This subject-matter does not appear in the Specification as accepted.