NOTES BY THE EDITOR. XQI 



an eruption of 1.5 minute's height takes place, to be 40, 690 C., 

 and from a protuberance of 3 minutes' height, 74, 910 C. 



The maximum velocities of streams of gas moving vertically or 

 horizontally in the chromosphere are from 40 to 120 English milea 

 per second. According to the mechanical theory of heat such ve- 

 locities of hydrogen necessitate differences of temperature amount- 

 ing to 40,690 C. Having shown that the explanation of the 

 eruptive protuberances necessitates the existence of a separating 

 stratum between the space from which they emanate and the 

 space into which they pass, we must assume a reference to its 

 physical condition that it cannot be gaseous, and must, therefore, 

 be .either solid or liquid. The former is improbable on account 

 of the high temperature ; it is therefore concluded that the sepa- 

 rating stratum consists of an incandescent liquid. 



In reference to the inner masses of hydrogen, bounded by that 

 stratum, two suppositions are possible : 1. The whole interior of 

 the sun is filled with incandescent hydrogen gas, which would 

 make the sun an immense bubble of hydrogen, surrounded by a 

 liquid glowing envelope. 2. The masses of hydrogen, bursting 

 out into protuberances, are local collections, in bubble-like cav- 

 erns, which form in the superficial layers of a liquid glowing mass, 

 and burst through when the presence of the confined gas in- 

 creases. 



Under the first supposition, stable equilibrium could only exist 

 if the specific gravity of the outer layer is less than that of the gas 

 below it. Since the density of a globe of gas, whose particles are 

 subject to Newton's and Mariotte's laws, increases towards its 

 centre, the specific gravity of the outer boundary layer must neces- 

 sarily be less than the mean specific gravity of the sun. But if we 

 take the mean specific gravity of the sun as the maximum of the 

 liquid outer layer, we would be obliged to assume that all deeper 

 layers, including the gaseous one immediately below, have the same 

 specific gravity. Then the interior of the sun could not consist of a 

 gas, but of an incompressible fluid. All these properties are clearly 

 a necessary consequence of the supposition that the specific grav- 

 ity of the compressed gases forming the protuberances reaches as 

 its maximum the mean specific gravity of the sun. 



In that case we must suppose, secondly, that the sun consists of 

 an incompressible liquid, near whose surface there are collections 

 of glowing masses of hydrogen, which break through bubble- 

 like caverns, as eruptive protuberances under certain differences 

 of pressure. 



