^98 COSMOS. 



accordingly, in the solar system, at one time void, at another 

 occupied by matter. All that has been advanced Avith re- 

 gard to the existence of a dark central body in the center 

 of gravity of double stars, or at least of one originally dark, 

 but faintly illuminated by the borrowed light of the planets 

 which revolve round it, belongs to the ever-enlarging realm 

 of mythical hypotheses. 



It is a more important consideration, and one more de- 

 serving of thorough investigation, that, on the supposition of 

 a revolving movement, not only of the whole of our planet- 

 ary system which changes its place, but also for the proper 

 motion of the fixed stars at their various distances, the cen- 

 ter of this revolving motion must be 90° distant^ from the 

 point toward which our solar system is moving. In this con- 

 nection of ideas, the position of stars possessing a great or 

 very small lyroj^er motion becomes of considerable moment. 

 Argelander has examined, with his usual caution and acute- 

 ness, the degree of probability with which we may seek for 

 a general center of attraction for our starry stratum in the 

 constellation of Perseus. f Madler, rejecting the hypothesis 

 of the existence of a central body preponderating in mass, 

 as the universal center of gravity, seeks the center of grav- 

 ity in the Pleiades, in the veiy center of this group, in or 

 nearl to the bright star ^ Tauri (Alcyone). The present is 



* Argelauder, ibid., p. 42 ; Madler, Centralsonne, s. 9, and Astr., s. 

 403. 



t Argelauder, ibid., p. 43 ; aud in Schum., Astr. Nachr., No. 566. 

 Guided'by no numerical investigations, but following the suggestions of 

 fancy, Kant long ago fixed upon Sirius, and Lambert upon the nebula 

 in the belt of Orion, as the central body of our starry stratum. (Struve, 

 Astr. StelL, p. 17, No. 19.) 



X Madler, Astr., s. 380, 400, 407, and 414 ; in his Centralsonne, 1846, 

 p. 4i-i7 ; in Untersuchun^en uber die Fixstern-Systeme, th. ii.. s. 183- 

 185. Alcyone is in R. A.'54° 30', Decl. 23° 36', for the year 1840. If 

 Alcyone's parallax were really 0"-0065, its distance would be equal to 

 3H million semi-diameters of the earth's orbit, and thus it w-ould be 



I 



fears to pass from Alcyone to the earth. The fancy of the Greeks de- 

 ighted itself in wild visions of the height of falls. In Hesiod's Theo- 

 gonia, V. 722-725, it is said, speaking of the fall of the Titans into Tar- 

 tarus: " If a brazen anvil were to fall from heaven nine days aud nine 

 nights long, it would reach the earth on the tenth." This descent of 

 the anvil in 777.600 seconds of time gives an equivalent in distance of 

 309,424 geographical miles (allowance being made, according to Galle's 

 calculation, for the considerable diminution in the force of attraction at 

 planetary distances), therefore H times the distance of the moon from 



