ASTROXO.MICAL \oTES. 283 



we entirely overlooked the exact fall in temperature on the 

 thermometer until it was too late. 



We are frequently reminded b\' astronomers, and other 

 philosophers that the sun is g"raduall\- cooling- down, and 

 tha.t the time is coming at some inconceivable distant date 

 when it will literally be burned out, \\hen the Earth and other 

 phmets of the Solar system will be without any life, light, or 

 heat — dead worlds. We remember the late Dr Grierson, at 

 one of the meetings of this Society, telling us that " the time 

 is coming when the last thatched snow-clad cottage will be 

 standing empty on the Equator." The same reasoning would 

 apply to every star and every system in the universe : that 

 every star is cooling down through constant radiation of 

 energy into space. 



After gi\ ing some considerable amount of thought to 

 this matter, I think that it is just possible that after the 

 evolution of the Solar system from Spiral Nebula, that the 

 immense heat de\eloped would bring the whole into an incan- 

 descent condition (perhaps appearing as a " new star " in 

 other parts of the universe), when a.fter another inconceivable 

 length of time, the constituents of the Solar system would cool 

 down by radiation to the temperature they now ha\"e. We 

 speak of the balance of Nature being upheld through natural 

 ag-encies. Is it not possible that a balance in the Stellar uni- 

 verse may be kept up on the same principle? We know that 

 the sun is constantly radiating" into space energy in the form of 

 liglit, heat, etc., and perhaps other emanations that we do not 

 understand ; and the portion of that emanation which is 

 received by the Earth and planets is quite infinitesimal in 

 proportion to the whole amount radiated. Then the question 

 arises — \\'hat becomes of that which is thrown into space? 

 When we think of the millions of stars which are doing" 

 exactly the same thing, another question is suggested. Is 

 it not possible that while all the stars of the universe are 

 constantly radiating" energy, they may at the same time be 

 constantly receiving emitted energy from other stars suffi- 

 cient to compensate for their individual emission, and for 

 their maintenance at a constant temperature? There are 

 many other questions suggested to the mind in connection 



