ASTRONOMY. 



15 



A discussion of the telescopic observations of the late 

 transit of Venus made by the British expeditions has been 

 laid before Parliament. In this preliminary result the inter- 

 nal contacts observed at five stations have been made use 

 of, viz. : Honolulu, ingress accelerated ; New Zealand, ingress 

 retarded very slightly; Rodriguez and Kerguelen, ingress 

 retarded ; Egypt (Mokattam, Suez, and Thebes), egress re- 

 tarded ; Rodriguez, egress retarded very slightly ; Kergue- 

 len, egress accelerated. The value of the sun's parallax thus 

 found is 8.760", with a probable error of 0.013", corresponding 

 to a distance of 93,300,000 miles, with a probable error of 

 140,000 miles. According to Christie, of Greenwich : "Al- 

 though there may be some small corrections to be applied 

 to the individual results for errors in the provisional longi- 

 tudes used, their amount can be but small, and it is hardly 

 conceivable that the mean value can be sensibly affected. 

 Nor is there any possibility of materially altering the re- 

 sult by another interpretation of the language of the ob- 

 servers concerned. We must, therefore, accept the fact that 

 these observations of the transit of Venus give a value for 

 the sun's parallax which is considerably less than most of 

 those which have been recently put forward, though still 

 decidedly larger than Encke's result. There remain, how- 

 ever, the observations made in India and Australia, which 

 will reinforce the rather meagre results for egress, and also 

 the measures of photographs which promise to give a very 

 accurate value of the parallax." 



Deichmuller, of Bonn, has published an investigation of the 

 circumstances of the transit of Venus in 1882 ; it has been com- 

 pared with a discussion lately published by Peter, of Leipzig. 



Mr. David Gill, of England, has taken up his residence at 

 Ascension Island, for the purpose of making heliometric ob- 

 servations of Mars to determine the solar parallax. The 

 heliometer to be employed is the one used by Mr. Gill in the 

 Transit of Venus Expedition of Lord Lindsay in 1874, in 

 which Juno was observed and the parallax 8.82" deduced. 

 This expedition is of great importance, in many ways, as 

 it is quite possible that from its results the best determina- 

 tion of solar parallax may be had, as the method employed 

 admits of great refinement. The support given to the ex- 

 pedition is also noteworthy, as the Royal Astronomical So- 



