16 Proceedings of tJte Royal Society of Victoria. 



is therefore an extremely complicated one. Any given 

 substance would on arriving at its critical temperature turn 

 to vapour, this vapour would exercise an explosive force on 

 the materials between it and the surface. There are between 

 sixty and seventy elements, and the critical temperature of 

 each one differs. The matter about the surface would be 

 upheaved or disturbed an indefinite number of times. This 

 would continually generate an enormous amount of heat. If 

 this is the case it is an almost hopeless task to compute the 

 duration of the sun's energy. It would depend partly on the 

 proportion in which the various elementary substances were 

 present, and ])artly on the rate of conductivity of the solid 

 materials deep down from the centre and the resistance 

 offered. Until the greatest possible amount of heat had 

 passed by conduction to the centre, and the vapours formed 

 had ]^e]formed work, we would not be justified in regarding 

 the sun as a body actually cooling. He is continually 

 parting with the energies, and their expenditure maintains 

 the heat. What is known of the phj'sical constitution of the 

 sun's surface would appear to support this view. There 

 would be a continual storing up of energy, the force of which 

 would be dependent on the amount of resistance to be 

 overcome. The suns[)ots and facultB with their periodicity 

 might be caused by the gathering up of the internal forces 

 during seasons, followed by outbursts relieving the internal 

 energies. The eruptive or metallic prominences whose 

 spectra show the lines of sodium, magnesium, barium, iron 

 and other metals, occasionally^ rise to a height of over 

 200,000 miles above the chromosphere. The velocity of the 

 motions of these prominences sometimes reaches 200 miles 

 a second. This points to the existence of enormous eruptive 

 forces in the sun's interior. We might regard the sunspots, 

 faculai, and eruptive prominences as analgous to terrestrial 

 volcanoes, the difference between tlie solar and terrestrial 

 forces being due to the greater intensity of the former, and 

 to the sun's surface being in an intensely lieated gaseous 

 condition. 



So far we have dealt with the sun himself and have not 

 considered the mode of formation of the planets. As the 

 nebula condensed heat would be generated by friction 

 between the solid particles themselves while falling, and the 

 more volatile substances would become vapourised, the less 

 easily melted parts would be enveloped in a gaseous 

 atmosphere, and the light particles would not fall so quickly as 



