52 A CENTURY'S PROGRESS IN ASTRONOMY. 



these maps have been recently superseded by 

 the investigations of Sir Joseph Norman Lockyer 

 (born 1836), and of the American physicist, 

 Henry Augustus Rowland (1848-1901). Row- 

 land largely increased our knowledge of the 

 elements in the solar atmosphere. 



The spectroscope had become, by 1868, a 

 recognised instrument of astronomical research, 

 and in that year it was applied during the 

 famous total eclipse, visible in India. There 

 were many eclipse problems, arising from the 

 observations made by the eclipse expeditions 

 of 1842, 1851, and 1860. The eclipse of 1851 

 had finally proved that the red flames seen 

 surrounding the Sun during total eclipses be- 

 longed to the Sun, and not to the Moon, as 

 many astronomers had believed. At the eclipse 

 of 1860, visible in Spain, the Italian astronomer, 

 Angelo Secchi (1818-1878), and the Englishman, 

 Warren De la Rue (1815-1889), secured photo- 

 graphs of the solar prominences. The problem of 

 1868 was the constitution of these prominences. 



Pierre Jules Cesar Janssen, born in Paris in 

 1824, was stationed at Guntoor, in India, to 

 observe the eclipse. He succeeded in observing 

 the spectrum of the prominences during the 

 progress of totality, and found it to be one of 

 bright lines, proving the gaseous nature of the 



