Astrolabes of the World
暂无分享,去创建一个
t h e R o y a l I t a l i a n N a v y takes the form of a precise handbook of observations by means of the astrolabe. I t gives the description and method of use of the J o b in instru ment and of the instrument constructed by the S. O. M. (So c ié t é d ’O p t iq u e e t d e M é c a n iq u e d e h a u t e p r é c is io n , Paris). For the computation of observations by prismatic astrolabe the Italian Hydrographie Institute has adopted the J o r d a n formula by means of which the computations of distance from the estimated position to the position line given by the astrolabe obser vation, may be easily estimated. An example of computation is given in the work. For the preparation of the programme of observations the Italian Hydrographic Institute has adopted a graphic procedure worked out by Admiral T o n t a ; this procedure, which makes use of stellar plans of the northern and southern hemispheres in stereo graph-polar projection and of a graph representing the almucantar of 30° zenithal dis tance corresponding to the station position, is described on pp. 40-45 of Professor F o r n i ’s publication ; by its means the list of sidereal times and azimuths of the different stars observable passing at the zenithal distance of 30° is very readily established.