A GIANT PLANET. IO/ 



the exceeding brilliancy of the surface of the planet. 

 In the same way the solar spots, if not surrounded by 

 the marvellous splendour of the sun's surface, would 

 doubtless appear as brilliant objects.' 



Next let us hear Secchi's account. ' On the evening 

 of February 3rd,' he says, ' I observed the transit of 

 the third satellite and that of its shadow. The satellite 

 seemed almost black when it was upon the middle of 

 the planet's disc, and notably smaller than its shadow, 

 which was visible at the same time ; one would have 

 estimated it at only one-half. In approaching the 

 edge the satellite disappeared, and reappeared soon 

 after, close by the edge, but as a bright point. This fact 

 is not a new one for the other satellites, but for the third 

 it is unique. This result shows also the great difference 

 of luminosity at the centre and near the edge of the 

 planet, a difference already confirmed by photography.' 



It is hardly necessary to point out how strikingly 

 these facts illustrate and confirm Dr. Zollner's observa- 

 tions. But they also supply fresh evidence of a very 

 interesting nature. 



Although a part of the difference dwelt on in 

 Secchi's closing words may be ascribed to the oblique 

 incidence of the light near the planet's edge, yet it 

 does not appear to me that the whole difference can be 

 thus explained. A difference so great that a satellite 

 appears as a bright point close by the planet's edge, 

 and almost black near the middle of the disc, suggests 

 that the light near the edge is not reinforced by the 

 inherent luminosity of our theory, that luminosity 



