458 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. SUPPLY BAY. 



The portable altazimuth, also by Troughton and Simms, was lent by 

 Mr. Warren De la Rue. The vertical circle was 12 inches in diameter, and 

 was read by two micrometer-microscopes to single seconds of arc. These 

 microscopes were supported at the extremity of a horizontal bar forming a 

 portion of the solid casting of the revolving body. There was one sensitive 

 zenith distance level, graduated with 40 divisions to the minute. There 

 appears to have been one vertical and one horizontal wire. 



This altazimuth was mounted close to the transit-instrument and under the 

 game roof, and with it the following results were obtained for colatitude : 



