216 



TRANSIT OF VENUS, 1874. KAILUA. 



The center of the mark was 76"-6 West of true North. (Table III.). 



"When making an observation of the mark, the position of the wire on the 

 image of the copper scale was estimated to the nearest tenth of a division ; 

 this was done with much greater accuracy than was to be expected. 



When no close circumpolar star has been observed, the azimuth-error and 

 clock-correction have been deduced from all the observed transits in the 

 following manner : 



If x be the azimuth-error and y the clock-correction corresponding to the 

 mean of the times, 



a = i 5S in' Stare N'P'D ' ( usua ^y termed the "Azimuth-factor"), 

 b = a quantity, in seconds of time, obtained by subtracting the star's 

 apparent Right Ascension from the clock time of transit corrected 

 for level and collimation, and, if necessary, for clock rate, 

 each star will give an equation of the form 



ax + y-\-b = o. 



Such equations have been solved by the method of least squares to obtain 

 the most probable values of x and y. 



In Table II. the extreme N.P.D.'s are given on each occasion of the employ- 

 ment of this method. 



Tables II. and III. exhibit the observed and adopted Error of Azimuth, 

 and the observations of the mark. 



The Azimuth was adjusted November 24 and 26, December 18 and 31. 



TRANSITS of STARS and of the MOON observed at KAILUA. 



The description at page 15 of the stars observed at Honolulu, the method 

 of reduction, and the arrangement of Table IV., applies to Kailua in every 

 particular. 



