202 COSMOS. 



Christian Mayer, the Manheim astronomer, has the great 

 merit of having first (1778) made the fixed stars a specia. 

 ohject of research, hy the sure method of actual ohservations. 

 The unfortunate choice of the term satellites of the fixed 

 stars, and the relations which he supposed to exist among 

 the stars between 2^ 30' and 2^ 55' distant from Arcturus. 

 exposed liim to bitter attacks from his cotemporaries, and 

 among tliese to the censure of the eminent mathematician, 

 Nicolaus Fuss. That dark planetary bodies should become 

 visible by reflected hght, at such an immense distance, was 

 certainly improbable. No value was set upon the results of 

 his carefully-conducted observations, because his theory of 

 the phenomena was rejected ; and yet Christian Mayer, in 

 his rejoinder to the attack of Father Maximilian Hell, Di- 

 rector of the Imperial Observatory at Vienna, expressly as- 

 serts "that the smaller stars, Avhich are so near the larger, 

 are either illuminated, naturally dark planets, or that both 

 of these cosmical bodies — the principal star and its compan- 

 ion — are self-luminous suns revolving round each other." 



a borrowed light coidd possibly be visible), we should then have the 

 means of discovering " Throughout the whole discussion he de- 

 nies that one of the two revolving stars can be a dark planet shining 

 with a reflected light, because both of them, notwithstanding their dis- 

 tance, are visible to us. Calling the larger of the two the " central 

 star," he compares the density of both with the density of our sun, and 

 merely uses the word '' satellite" relatively to the idea of revolution cr 

 of reciprocal motion; he speaks of the "greatest apparent elongation 

 of those stai-s that revolve about others as satellites." He further says, 

 at p. 243 and 249 : " We may conclude with the highest probability 

 (the odds against the contrary opinion being many million millions to 

 one) that stars form a kind of system by mutual gravitation. It is high- 

 ly probable in particular, and next to a certainty in general, that such 

 double stars as appear to consist of two or more stars placed near to- 

 gether are under the influence of some general law, such, perhaps, as 



gravity " (Consult also Arago, in the Annuair-e povr 1834, p. 308, 



and Ann. 1842, p. 400.) No great reliance can be placed on the indi- 

 vidual numerical results of the calculus of probabilities given by Michell, 

 as the hypotheses that there are 230 stars in the heavens which, in in- 

 tensity of light, are equal to (3 Capricorni, >iid 1500 equal to the six 

 gi'eater stars of the Pleiades, are manifestly incorrect. The ingenious 

 cosmological treatise of John Michell ends with a veiy bold attempt to 

 explain the scintillation of the fixed stars by a kind of " pulsation in 

 material eSluxes of light" — an elucidation not more happy than that 

 which Simon Marius, one of the discoverers of Jupiter's satellites (eee 

 Cosmos, vol. ii., p. 320) has given at the end of his Munius Joviaii^ 

 (1614). But Michell has the merit of having called attention to the 

 fact (p. 263) that the scintillation of stars is always accompanied by a 

 change of color. '' Besides their brightness, there is in the scintillation 

 cf the fixed stai's a change of color." ( Vide supra.) 



