OF THE COSMOS. MOTION OF THE SOLAR SYSTEM. 197 



and Saturn, sometimes within the corporeal circumference 

 of the Sun, and sometimes (and this is the more frequent 

 case) on the outside of that circumference. ( 324 ) Thus the 

 centre of gravity, which in the double stars is void, is in 

 the solar system sometimes void, and sometimes occupied 

 by matter. All that has been said respecting the possi- 

 bility of the assumption of a dark central body in the centre 

 of gravity of the double stars, or of planets originally dark 

 but faintly illuminated by foreign light revolving around 

 them, belongs to the wide domain of mythical hypothesis. 



It is a graver consideration, and one more deserving of a 

 thorough examination, that, if we assume a movement of 

 revolution, both for our own entire solar system, and for 

 all the proper motions of the fixed stars situated at such 

 widely different distances from us, the centrum of this re- 

 volving motion must be 90 from the point ( 325 ) towards 

 which our solar system is moving. In reference to the 

 combination of ideas which is here introduced, the situation 

 of the stars, which have, on the one hand, a very consider- 

 able, or, on the other hand, a very slight proper motion, 

 becomes of great moment. Argelander has cautiously, 

 and with his own peculiar sagacity, tested the degree of 

 probability with which, in our own sidereal stratum, a 

 general centrum of attraction might be sought for in the 

 sidereal constellation of Perseus. ( 326 ) M'adler, rejecting the 

 hypothesis of a central body occupying the place of the 

 general centre of gravity, and being itself of preponderating 

 mass, seeks the centre of gravity in the group of the 

 Pleiades, and in the middle of the group, in or near( 327 ) 

 the bright star r\ Tauri (Alcyone). This work is not the 

 place for examining the degree of probability, on the one 



