14 VESTIGES OF THE 



in which line our eye hcas to traverse the vacant central 

 space. Nor is this all. Sir William Ilerschel, so early 

 as 1783, detected a motion in our solar system with 

 respect to the stars, and announced that it was tending 

 towards the star X, in the constellation Hercules. This 

 has been generally verified by recent and more exact cal- 

 culations,* which fix on a point in Hercules, near the 

 star 143 of the lyth hour, according to Piozzi's catalogue, 

 as that towards which our sun is proceeding. It is, 

 therefore, receding from the inner edge of the ring. 

 Motions of this kind, through such vast regions of space, 

 must be long in producing any change sensible to the in- 

 habitants of our jDlanet, and it is not easy to grasp their 

 general character ; but grounds have nevertheless been 

 found for supposing that not only our sun, but the other 

 suns of the system, pursue a wavy course round the ring 

 from west to east, crossing and recrossing tlic middle of 

 the annular circle. " Some stars will depart more, others 

 less, from either side of the circumference of equilibrium, 

 according to the places in which they are situated, and 

 according to the direction and the velocity Avith which 

 they are put in motion. Our sun is probably one of 

 those which depart furthest from it, and descend furthest 

 into the empty S23ace within the ring."t According to 

 this viev/, a time may come v/hen we shall be much more 

 in the thick of the stars of our astral system than we are 

 now, and have of course much more brilliant nocturnal 

 skies ; but it mny be countless ages before the eyes which 

 are to see this added resplendence shall exist. 



The evidence of the existence of other astral systems 



* Mado by M. Argelandci-, lute director of tlie Ob crvalory at Abo. 



t Professor Mossotti, on the Constitution of the Sidereal iSysteni, 

 of wliicli tlie 8un forms a part : Londr. ^, Edinhurgli^ an:! Dublin 

 J^hilosojjhica' Miujazinc, February 1843. 



