62 A CENTURY'S PROGRESS IN ASTRONOMY. 



French, German, American, English, Scottish, 

 Italian, Russian, and Dutch astronomers, and 

 it was hoped that the solar parallax would be 

 accurately measured once for all. However, the 

 transit, although favoured with good weather, 

 was not successful, owing to the difficulty of 

 making exact measurements, by reason of the 

 illumination and refraction in the atmosphere 

 of Venus. Accordingly the values deduced for 

 the parallax were far from unanimous. The 

 transit of 1882 was not observed so extensively, 

 as astronomers had found the transit of Venus 

 to be by no means the best method. In 1877 

 Sir David Gill (born 1843), the great Scottish 

 astronomer, determined the solar parallax suc- 

 cessfully from measures of the parallax of Mars 

 in opposition. His value was 8 "'7 8, correspond- 

 ing to 93,080,000 miles. Some years previous 

 to this Johann Gottfried Galle (born 1812), the 

 German astronomer, had, from measurements 

 of the parallax of the asteroid Flora, deduced 

 a solar parallax of 8" '8 7. Gill's work at the 

 Cape in 1888, on the Asteroids, was successful 

 in giving a more accurate value than the transit 

 of Venus: in 1900 and 1901 measures of the 

 parallax of the asteroid Eros, the nearest minor 

 planet, were made by many different observa- 

 tories, and agree with the other results. The 



