THE DIURNAL VARIATION OF LATITUDE AND LONGITUDE OBTAINED WITH AN ASTROLABE

From the analysis of the difference between two neighbouring groups obtained with an astrolabe in the same night, the existance (with regard to both latitude and longitude) of the rate of change of the difference between two neighbouring star groups is discovered. A study of the rule of the diurnal variation of latitude and longitude, obtained with the astrolabe in Shanghai, leads us to the hypothesis that the diurnal variation of latitude and that of longitude are the two components of the displace-ment of the apparent zenith.