406 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAY. 



a site on the southern side of the entrance of an inlet or bay, in the N.W. 

 corner of the Sound, in lat. 49. 25 / -2 S., long. 69. 53' '5 E. This inlet 

 was named OBSERVATORY BAY, and is shown in the plan of Royal Sound 

 (Plate XVI.), as surveyed by Lieutenant VIVIAN, R.N., of H.M.S. Volage. 



The wooden observatories and dwelling-house were erected on nearly level 

 ground, about 50 feet above the sea. Constant snow-storms and rains 

 interrupted the work of landing and erecting the huts and instruments ; the 

 land had to be drained, roads made, and a pier constructed ; but, with the 

 efficient assistance rendered by Captain Fairfax and the officers and men of 

 H.M.S. Volage, most of the work on shore was finished by October 26, when 

 the first observations were taken. 



The Transit clock, by B. Dent and Co., of London, numbered 1915, was 

 similar to that used at Honolulu. Its tripod rested upon stakes driven 

 deeply into the ground through holes cut in the flooring of the observatory. 



MERIDIONAL OBSERVATIONS. 



The Transit instrument, its piers, the hanging level, and the wooden 

 observatory, were, in every respect, similar to those used at the other head 

 stations, and have been fully described in Part I., at page 9 et seq. 



For the foundations of the transit pier, the subsoil was excavated until the 

 rock was reached. A bed of concrete was laid on the rock and levelled. 

 When this had set, a brick pier was built up to the level of the ground to 

 receive the great stone. The building of the piers was much impeded by 

 the rains ; and, although all possible care was taken with the foundations, 

 subsequent observations proved that the instrument was unstable at all times, 

 but especially after heavy rains. The instrument was fairly in the meridian 

 by November 3. 



The value of one revolution of the eye-piece micrometer-screw (which 

 carried all five wires of the reticule) was found at different times, from 

 numerous observations of close circumpolar stars, the mean value being 

 56"'09. The integer revolutions were numbered in the observing books so 

 as to increase when the Avire was carried towards the screw head ; the center 

 wire coincided approximately with the optic axis when the reading was 20 r- 5. 

 The position of the transit-axis is always denoted by the record of the 

 micrometer-screw head being on the east or west side of the telescope. 



