384 TRANSIT OF VENUS, 1874. RODRIGUEZ. POINT COTON. 



OBSERVATIONS at POINT COTON, RODRIGUEZ, by Commander WILLIAM J. L. 

 WHARTON, R.N., with a 2f Refractor by Troughton and Simms. 



The observation spot was 20 feet from the edge of the sea cliff (30 feet) of 

 Point Coton that faces the East, with the summit of the inshore cliff (where 

 the triangulation beacon was) S. 73. 03' "W. (true) 185 feet. The northern 

 point of Point Coton is (by chart) 926 feet. By triangulation, the position 

 was 0'. 32"-28 South and 4'. 14"'69 (diff. long.) East of the Altazimuth Hut 

 at the main observatory on Point Venus. 



The exact spot is marked by an iron stake fixed into the rock with lead. 



On the 8th December three chronometers were conveyed to Point Coton 

 by water, after being compared with the Transit clock of the Point Venus 

 observatory ; intercomparisons on arrival showed they had suffered no shocks. 



Time was checked the same evening by rockets thrown up in the center 

 of the island ; two hours after the transit, the chronometers were again com- 

 pared with the Transit clock, having been re-conveyed by water to Point 

 Venus. 



Time was taken by Nav. Lieut. Langdon, R.N., from the Solar chronometer 

 Poole 1086. 



The morning of the 9th was perfectly calm, and generally clear, but several 

 clouds hung to the S.E., and threatened to cover the Sun at the moment of 

 contact. About a minute after the critical phenomenon the Sun was hid 

 from view for some minutes. The limb of the Sun was considerably agitated, 

 probably by the rays passing through the thinner portions of the clouds 

 above-mentioned ; as the line of sight passed over no land, and the surf on 

 the reef at 300 yards distance was quiet. 



The planet was first seen at 9 h . 28 m . At 9 h . 52 m . I observed that the outer 

 limb of Venus farthest from the Sun was illuminated ; as I was not on the 

 look out for this, it may have been visible earlier. At the same time I saw 

 a distinct cone of shadow thrown away into space, but for no great distance, 

 on the line joining centers of Sun and planet. (See Diagram I.) 



The illumination of the outer limb of Venus broadened and increased in 

 brilliancy up to simple internal contact, when for a moment it seemed as if 

 there was to be no drop ; Venus being apparently visible on the edge of the 

 Sun, with light all round her. (See Diagram II.) 



Immediately after this a blackish haze was discernible joining the planet 

 and the continuation of the Sun's limb ; but from the agitation of the limb, 



