Notices respecting New Books. 369 



ray. He does not indeed say this ; but we gather the idea from 

 many passages in his Essays. 



Next in importance to the Milky Way is the zone of lucid stars 

 which fringes, and indeed intersects the Galaxy as seen from our 

 stand-point on earth. It is in the treatment of this zone of lucid 

 stars that we trace the commencement of Mr. Proctor's develop- 

 ment of his "views of the starry heavens. This zone he conceives 

 as consisting of a stream of stars, the components of which are im- 

 mersed in, and intimately associated with, the Milky Way. In 

 connexion with this association, Mr. Proctor lays considerable stress 

 on the irregularity of outline of the Galaxy produced by the long 

 lateral offsets consisting of wisps and sprays of the really small 

 stars composing that wonderful zone, and adduces instances of 

 lucid stars occupying the apices of sharply denned projections from 

 the Milky Way. 



Closely associated with the galactic zone are found those remark- 

 able objects in the heavens, the irregular nebulae, which, with very 

 few exceptions, as stated by Mr. Proctor, are found on the Milky 

 Way. " Correspondiug/'says our author on p. 86, "to the association 

 between the Milky Way and lucid stars is a phenomenon which falls 

 here to be considered .... the irregular nebulas .... the wisps and 

 sprays of nebulous light which stream from the central convolu- 

 tions of such nebulae correspond, quite closely in many instances, 

 with streams of small fixed stars. In many of these nebulae also 

 there are streams of faint nebulosity extending towards fixed stars, 

 and acquiring a sudden brightness around them. In connexion 

 with the views of Mr. Proctor, based on these apparent associations, 

 we would remark that our author, in our opinion, depends almost 

 solely on the application of the theory of probabilities for substan- 

 tiating his views. Now probability is not proof ; and before a 

 theory can or ought to be received as an exponent of natural phe- 

 nomena, it is necessary that it be demonstrated ; and until this is 

 effected, the theory remains in the category of guesses. A true guess 

 it may be nevertheless ; but it requires crucial observation to estab- 

 lish it. In the quotation from p. 83 Mr. Proctor speaks of the 

 G-alaxy as being separated from us by a comparatively starless in- 

 terval ; but in no part of the work does he indicate, as we can find, 

 where this starless interval is situated. We know the sun exists 

 in a barren or starless portion of space. For example, in a region 

 of 120 billions of miles in diameter four stars only, three of which 

 are lucid, are found ; beyond this space the more lucid stars are ar- 

 ranged as a ring, nearly, but not quite, in the same visual direction 

 as the Galaxy. In addition, there are many lucid stars scattered 

 over the heavens apparently unassociated with the Milky Way. 

 Now does the starless interval of which Mr. Proctor speaks exist 

 between the lucid stars and the Galaxy ? or is it the barren space 

 in which the sun is situated? Mr. Proctor's remarks on p. 86 are 

 opposed to the idea of a starless space between the lucid stars and 

 the Milky Way, the brighter stars drawing the smaller stars of the 

 Galaxy towards them. 



Phil Mag. S. 4. Vol. 47. No. 313. May 1874. 2 B 



