390 British Association. 



and which return at stated intervals, are extremely useful, as be- 

 ing likely to disclose facts of which, but for them, we should pos- 

 sibly have ever remained ignorant. Thus, for example, when the 

 comet of Encke, which performs its revolution in a period of a 

 little more than three years, was observed at each return, it dis- 

 closed the important and unexpected fact, that its motion was 

 continually accelerated. At each successive approach to the sun 

 it arrives at its perihelion sooner and sooner ; and there is no 

 way of accounting for this so satisfactory as that of supposing 

 that the space, in which the planetary and cometary motions are 

 performed, is everywhere pervaded by a very rarefied atmosphere 

 or ether, so thin as to exercise no perceptible effect on the move- 

 ments of massive solid bodies like the planets, but substantial 

 enough to exert a very important influence on more attenuated 

 subt^tances moving with great velocity. The effect of the resist- 

 ance of the ether is to retard the tangential motion, and 

 allow the attractive force of gravity to draw the body nearer 

 1o the sun, by which the dimensions of the orbit are continually 

 contracted and the velocity in it augmented. The final result 

 will be that, after the lapse of ages, this comot will fall into the 

 sun ; this body, a mere hazy cloud, continually flickering as it 

 were like a celestial moth round the great luminary, is at some 

 distant period destined to be mercilessly consumed. Now the 

 discovery of this ether is deeply interesting as bearing on other 

 important physical questions, such as the undulatory theory of 

 light ; and the probability of the future absorption of comets by 

 the sun is important as connected with a very interesting specu- 

 lation by Prof. William Thomson, who has suggested that the 

 heat and light of the sun may be from time to time replenished 

 by the falling in and absorption of countless meteors which circu- 

 late round him ; and here we have a cause revealed which may 

 accelerate or produce such an event. 



Luminous bodies in the Sun. 



On the 1st of September last, at llh 18m a. m., a distinguished 

 astronomer, Mr. Carrington, had directed his telescope to the 

 sun, and was engaged in observing his spots, when suddenly two 

 intensely luminous bodies burst into view on its surface. They 

 moved side by side through a space of about 35,000 miles, first 

 increasing in brightness, then fading away ; in five minutes they 

 had vanished. They did not alter the shape of a group of large 



