268 Work for the Telescope. 



but if we may credit the statements of a far inferior observer, 

 De-Vico, who saw a lucid point adhering to the opened ring 

 in 1840 and 1842, it can no longer be maintained upon any 

 ground, and the ring must be considered fixed. How to account 

 for its stable equilibrium and permanency would then be a diffi- 

 culty indeed ; for even with the powerful aid of rotation it has 

 driven the American mathematicians (who have especially in- 

 vestigated the subject) from the old idea of solidity; Pierce 

 taking refuge in the supposition of a fluid, and Maxwell in an 

 aggregation of unconnected particles. The great Roman ob- 

 server, Secchi, inclines to the idea of a gaseous or vaporous 

 constitution. The faint visibility of the dark side of the ring, 

 when it has been turned towards us, which was remarked by 

 Herschel I. in 1789, and by Bond and Dawes in 1848, is an 

 additional puzzle, especially the coppery tinge which was 

 detected in it by the latter observer. It seems, from Bond's 

 investigations, that it cannot arise from a twilight produced by 

 an atmosphere surrounding the ring; nor is the direction of 

 the Sun's rays favourable to the idea of a slight transparency, 

 which otherwise its astonishing thinness would render very 

 probable. Almost everything connected with this wonderful 

 appendage seems at present involved in impenetrable mystery. 



DOUBLE STARS. 



Before offering to the reader a list of beautiful or interesting- 

 double stars,* we shall repeat what was stated at the close of the 

 previous paper, that the possessors of even small telescopes will 

 find many of them within their range, though of course limited 

 apertures will detract from their brilliancy and distinctness. 

 Admiral Smyth has assured us that the majority of the binary 

 pans may be reached with an object-glass of 3| inches in dia- 

 meter, and that many of them may be beautifully seen with 

 2 1 inches ; some of them he found distinctly visible with only 

 two inches. Even the common little hand telescope, if good, 

 may be turned to some account by any one who will adapt to it 

 a deep astronomical eye-piece, and a small amount of skill in 

 such matters will enable this to be done, and a suitable stand 

 to be added, at a trifling expense. As an illustration of what 

 might be effected in this way, I may mention that I have thus 

 seen not only Mizar, but even Castor, of course in feeble light, 

 but very well defined, with an object-glass of only 1-J- inch. It 

 is possible indeed that with inferior optical means our first view 

 may not answer our expectations ; but the same great master, to 



* Sec an " Introductory Paper on Double Stars," Intellectual Ohserver, 

 p. 143. J i 



