CHAP. XIII.] OBSERVATIONS FOR ERROR 



315 



This method eliminates that portion of the rate of the 

 sidereal standard on mean solar time which is due to the 

 acceleration of sidereal time on mean solar time. It thus 

 enables the rate of the mean solar chronometer to be compared 

 with that of the solar sidereal clock reduced to mean solar time, 

 besides giving smaller quantities to deal with. 



The comparison at apparent noon may be worked up equally 

 well by treating the four comparisons in the ordinary manner, 

 as stated on p. 312. 



TABLE I. 



Table for valuing Sets of Equal Altitudes. 



The weight to be given to the results of each observer's f^^^^J' 

 observations in determining the final mean result presents some Values of 

 difficulty ; but it must obviously have some relation to the Altitudes 

 number of observations in each set, and the variation in the by differ- 

 sums of the seconds of middle time of the observations com- aorvpr« 



