On the upper surface of the 1st plate is horizontal altitude dial of pelican-type 4-12-8 (gnomon is missing). On the 1st plate are ring scale (0)-12(0)-12 of all-purpose equatorial dial; latitude selection scale is on the reverse side of the plate (0-80°) , with devisions in 1°(to 40), in 2°(40-60), in 5°(60-80)). Here is sidereal clock (nocturnal), combined with lunar phase indicator. Around compass box in the 2nd plate is scale of horizontal dial with thread gnomon 5-12-7 for latitude about 48°,5. On the bottom of the compass is degree scale and table with alphabetic list of 18 French cities and their latitudes. On the reverse side of the 2nd plate is perpetual calendar - metallic rotating disc.