GB1216317A - Improvements in planispheres - Google Patents

Abstract

1,216,317. Planispheres. IDA JANE EISENHAUER TRUST, W. A. EISENHAUER, W. P. ELLWOOD, and L. E. EISENHAUER, [trading as EISENHAUER MFG. CO.]. 12 Dec., 1967 [12 Dec., 1966], No. 56491/67. Headings G4B and G5G. A planisphere includes at least two concentric discs rotatable relative to one another, the discs being a sky map disc 12 having indications of the heavenly bodies representative of the celestial sphere thereon and an annular date scale 42, and a local time disc 16 having a local time scale 64 around its periphery and a sun indication 75 at the noon position; a mask 14 pivotable about the axis of rotation of the discs and including a transparent portion 46 the edge 48 of which represents the horizon of an observer at a predetermined latitude (as shown 42‹ N.); a line 36 representing the meridian of an observer on the transparent portion; and a reference rule 26 pivotable about the axis of rotation of the discs and positioned between the mask and the sky map disc. The planisphere also includes a standard time disc 18; a navigation disc 20 having a number of scales for navigation purposes; and 28-day and 32-day moon phase discs 22, 24. The reference rule 26 is transparent and has an indicating line 70 thereon. The local time disc 16 further includes representations 66; 67 of the 28-day and 32-day moon phases. To demonstrate the portion of the heavens which may be observed at a particular time on a particular date, the sky map disc 12 is rotated until the particular date on the scale 42 is adjacent the sun indication 75. Then rotation of the mask 14 until an indicator line 58 indicates the time of day on the scale 64 will expose through the transparent portion 46 the desired view. To find the rising and setting time of the sun on a particular date the sky map disc is rotated to bring the date adjacent the sun indication. The mask 14 is rotated until line 58 is aligned with the neon point on the time scale 64. The rule 26 is rotated to fix the point at which the meridian representation 36 intersects the ecliptic 40. The mask is moved clockwise or anticlockwise until line 48 meets the fixed point and then the time of setting or rising indicated by the line 58 can be read off from the scale 64. Other uses of the planisphere include finding the rising and setting times of any other celestial body; the declination and altitude of the sun; the meridian angle of any celestial body; and moon phases.