Chacornac on the Volcanoes of the Sun. 167 



thinks not consistent with the supposition of a liquid medium. 

 It was evidently a cloudy or gaseous one, able, by sudden 

 condensation, to form a relative vacuum, and occasion the 

 precipitation of fresh atmospheric layers upon the photosphere, 

 and the consequent formation of spots. Spiral gyratory move- 

 ments indicated this kind of action. Moreover, the spots 

 exhibited a disposition more or less striking to form gulfs, into 

 which the photospheric matter descended. 



In order to have superficial currents in a fluid spherical 

 mass, it seems necessary that there should be a break in the 

 decreasing density of its layers, and that there should be an 

 abrupt transition, as in the case of the atmospheres of Jupiter, 

 Saturn, or the Earth, which rest upon a solid surface, and 

 likewise a cause for the variation of the temperature of its 

 layers. From these and other considerations, M. Chacornac 

 concludes that it is an atmosphere with which our observations 

 have to do. 



The nuclei, in which great and feebly -luminous depths are 

 seen, disappear as if by evaporation — they dissipate themselves 

 like atmospheric clouds. The same phenomena are exhibited 

 in deep as in superficial layers, and who does not see in this 

 order of facts an explanation of the immense cavities into 

 which faculas are precipitated in torrents. Nothing is more 

 simple than these fusions and rapid falling of little spots into 

 big ones. In the region in which a vacuum is made, that is to 

 say in a spot, the cloudy layers are precipitated in the liquid 

 form on to the surface of the central body, or perhaps these 

 vapours in a vesicular state are vaporized and dissolved so as 

 to occasion a vacuum in which the superior or adjacent layers 

 are swallowed up. 



M. Chacornac observes that the descending currents in 

 these cases must have great force to draw with them, as he 

 has seen, matters possessing a horizontal velocity of 550 metres 

 in a second. 



The mobility of the spots and the rapidity of their changes 

 are regarded by M. Chacornac as opposed to the conception 

 of a resisting medium, and still more so to rents in a solid 

 crust. 



"When a great spot is forming, all the surrounding parts 

 are dragged into the gulf, into which also fall adjacent spots 

 of small dimensions. 



If a spot is solitary it assumes the regular form of a funnel, 

 and the ilocculent matter is distributed in channels round the 

 whirlpool orifice (orifice turbine). 



M. Chacornac does not deny the existence of ascending 

 currents, though what is observed only proves the operation 

 of descending currents. All spots, for example, are cavities 



