106 A CENTURY'S PROGRESS IN ASTRONOMY. 



for negative conclusions as to its nature. It 

 certainly did not represent the outpourings of a 

 Jovian volcano ; it was in no sense attached to 

 the Jovian soil if the phrase have any applica- 

 tion to the planet ; it was not a mere disclosure 

 of a glowing mass elsewhere seethed over by 

 rolling vapours." 



In 1870 Arthur Cowper Ranyard (1845-1894), 

 the well-known English astronomer, began to 

 collect records of unusual phenomena on the 

 Jovian disc to see if any period regulated their 

 appearance. He came to the conclusion that, 

 on the whole, there was harmony between the 

 markings on Jupiter and the eleven-year period 

 on the Sun. The theory of inherent light in 

 Jupiter, however, has not been confirmed. The 

 great planet was examined spectroscopically by 

 Huggins from 1862 to 1864, and by Vogel from 

 1871 to 1873. The spectrum showed, in addition 

 to the lines of reflected sunlight, some lines 

 indicating aqueous vapour, and others which 

 have not been identified with any terrestrial sub- 

 stance. A photographic study of the spectrum 

 of Jupiter was made at the Lowell Observatory 

 by Slipher in 1904, probably the most exhaustive 

 investigation on the subject. The spectroscope 

 has, however, given little support to the theory 

 of inherent light, and " we are driven to con- 



