160 A CENTURY'S PROGRESS IN ASTRONOMY. 



include 133,659 stars in the southern hemisphere, 

 by his assistant Eduard Schonfeld (1828-1891), 

 who succeeded him in 1875 as director of Bonn 

 Observatory, where he died in 1891. Meanwhile 

 a greater undertaking was commenced in 1865 by 

 the Astronomische Gesellschaft. This was the 

 co-operation of thirteen observatories in Europe 

 and America for the exact determination of the 

 places of 100,000 of Argelander's stars. 



In the southern hemisphere, working at Cor- 

 dova in Argentina, was the great American 

 astronomer, Gould, whose c Uranometria Argen- 

 tina/ published in 1879, gives the magnitudes 

 of 8198 stars, and whose Argentine General 

 Catalogue, containing reference of 32,448 stars, 

 was published in 1886. The late Radcliffe ob- 

 server, Stone, published a useful catalogue in 

 1880 from his observations at the Cape. 



The application of photography to the work 

 of star - charting dates from 1882, when Gill 

 photographed the comet of 1882, and was struck 

 with the distinctness of the stars on the back- 

 ground. For some time he had contemplated the 

 extension of the * Durchmusterung,' from the 

 point where Schonfeld left it, to the southern 

 pole, and the idea struck him to utilise phot- 

 ography for the purpose. In 1885, accordingly, 

 Gill commenced work, and in four years all the 



