20 



TRANSIT OF VENUS, 1874. HONOLULU. 



The distance of the wire C from the mean of the wires was also found, 

 from the times of 90 vertical transits, to be -00479 of the interval from 

 A to E. Taking this interval at 734"'3, C is distant 3"'52 from the mean. 

 The value 3"'76 has been adopted, and for convenience has been applied to 

 the zenith point, which is always greater by this amount for transits over all 

 the wires than for observations with the center wire only. 



50. The mean corrections for the runs of the four micrometers for 100" 

 were obtained as follows : 



The mean 0"'21 has been adopted throughout. 



51. The Altazimuth pier was 103 feet east of the Transit pier, corresponding 

 to a difference of time of O s> 074. This correction should have been applied 

 to the Altazimuth clock-error, but it was overlooked until the reductions had 

 proceeded so far that it was more convenient afterwards to apply the 

 necessary correction to the longitude (see page 27). 



52. The Errors and Hourly Rates of the Altazimuth Clock used in reducing 

 the zenith-distance observations are shown in Table VI. All the comparisons 

 of the solar half-seconds chronometer with the two clocks were made at the 

 instant when the beats coincided. The clock was made by E. Dent and Co. ; 

 the pendulum rod was of wood. It was compared with the Transit Clock 

 before and after every set of observations with the Altazimuth. 



THE LATITUDE OF THE ALTAZIMUTH PIER. 



53. The latitude was determined with great care, with the object of serving 

 as a point of reference for the Trigonometrical Survey of the kingdom of 

 HAWAII undertaken by the Government of His Majesty King KALAKAUA, and 



