5 o THE POPULAR SCIENCE MONTHLY. 



be found in their favor. But, so soon as we regard Saturn's whole 

 globe as in a state of intense heat, and his belt-system as indicating 

 the continual action of forces of enormous activity, we no longer find 

 any difficulty in understanding the possibility of changes such as Sir 

 W. Herschel, Sir G. Airy, the Bonds, and others of like observing 

 skill, have seen with some of the finest reflecting and refracting tele- 

 scopes ever constructed by man. Nay, we may even go further, and 

 find in solar phenomena certain reasons for believing that Saturn's 

 globe would be subjected to precisely such changes.* It appears to 

 have been rendered extremely probable by Secchi and others, that our 

 sun's globe varies in dimensions under the varying influences to which 

 he is subjected. At the height of the spot-period the sun seems to be 

 reduced in diameter, w^hile his colored sierra is deeper, and the red 

 prominences are larger than usual, the reverse holding at the time 

 when the sun has no spots or few. Of course this is not understood 

 as implying a real change in the quantity of solar matter, but only as 

 indicating the varying level at which the solar cloud-envelope lies. We 

 may safely assume that these changes, which correspond to the great 

 spot-period, affect chiefly the spot-zones which lie in the parts of the 

 sun's globe corresponding to our temperate zones ; but, for the same 

 reasons that the sun's globe is perfectly spherical so far as measure- 

 ments can be depended upon, namely, because of its relatively slow 

 rotation — such differences would be too slight to be measurable. Re- 

 garding Saturn, then, as we have already been compelled to do for 

 other reasons, as resembling the sun so far that he is in an intensely 

 heated condition, we see grounds for believing that his temperate zones 

 would be exposed to variations of level (cloud-level), which at times 

 might be very considerable, and thus discernible from our earth. For, 

 owing to his rapid rotation on his axis, all such effects would be rela- 

 tively greater than on a slowly rotating orb like the sun ; and in fact 

 we recognize this distinction in the great compression of Saturn's globe. 

 Moreover, if we regard the waxing and waning of the solar spots as 

 associated with the motions of the members of the sun's family, we 

 can well understand that the members of Saturn's family, which lie so 

 much nearer to him compared with his own dimensions, should produce 

 more remarkable effects. 1 But, whether this be so or not, it is certain 



1 It must not be understood that in thus speaking we countenance the theory that 

 either the planets produce the sun-spots, or the satellites of Saturn effect the remark- 

 able changes we have been dealing with. The real causes of all solar phenomena must 

 be sought in the sun's own globe ; and Saturnian phenomena are in the main, we have 

 little doubt, produced by Saturnian action. But even as our moon (probably) exerts an 

 influence on the occurrence of earthquakes and volcanoes, not by her own attraction 

 directly, but by affecting the balance between terrestrial forces, so it may well be that 

 the planets indirectly affect the sun's condition, and that the Saturnian satellites even 

 more effectually act upon Saturn. It would be extremely interesting to inquire whether 

 any connection can be traced between the changes of the Saturnian belts and the mo- 

 tions of his satellites. Or the inquiry might be more readily and quite as effectually 

 applied to Jupiter and his system. 



