March 26, 188 5] 



NA TURE 



4^5 



SA TURN 



1 I' is to be hoped that Continental observers may have 

 ■*• been more favoured than ourselves with opportunities 

 <)( scrutinising that grand display which has been for 

 time presented to us by this, the most wonderful of 

 all the solar train. For more than one reason the almost 

 unbroken persistence of that vaporous shroud which has 

 long been investing our unfortunate sky is matter of 

 especial regret. The broad development of that system 

 in all its equally strange and beautiful detail ; — its lofty 

 culmination in our midnight heaven ; — the probability 

 that many who might look upon it now may never witness 

 its return to a similar position of advantage — all find their 

 place in the account. We can only now look for intelli- 

 gence from other quarters, and hope that something more 

 cheering may yet be in store for ourselves, before the 

 advancing twilight steals away our opportunities ; and 

 that possibly, before these remarks meet the public eye, 

 a change may have supervened to gladden the heart of 

 the British observer. 



Few of us, probably, would be likely to express our- 

 selves as an individual once did, who, having for the first 

 time seen Saturn through a good telescope, turned hastily 

 away with a fervent aspiration that he might never see 

 such a sight as that again ! But the feeling that broke 

 out in so grotesque a fashion is not altogether unintellig- 

 ible. Many objects are more imposing in magnitude or 

 brilliancy : none rival it in the impression of surprise. It 

 is absolutely unique. Nothing else resembles it or ap- 

 proaches it in the whole visible creation. But this is not 

 all. Our first impression of astonishment will be suc- 

 ceeded by the demands of a legitimate curiosity, and we 

 shall begin to gaze upon that most charming combination 

 of elegant outline and varied shading, not merely as a 

 subject of admiration, but of close and careful study : we 

 shall naturally inquire how far we understand what we 

 are permitted to see, and how far that great mystery has 

 been penetrated by the modern unrivalled extension of 

 optical power. And here we may feel some disappoint- 

 ment when we are forced to admit that little correspond- 

 ing advance in knowledge has waited on the increased 

 means of investigation. There was an early dawn of 

 hope and promise after the elder Herschel had shown 

 what telescopes could do. Dawes, Lassell, Bond, De la 

 Rue, Struve, not to mention others, at once overleaped 

 all previous barriers, and showed how full that marvellous 

 whole is, of not less surprising detail. But it is not 

 encouraging to note how little progress, comparatively 

 speaking, has been made of later years. With advantages 

 so incontestably superior, what have we detected, on the 

 whole, more than what passed before the attention of a 

 previous generation ? Take, for instance, the beautiful 

 designs of De la Rue in 1S52 and 1S56 ; or the elaborate 

 memoir of the observers at Harvard, published in 1857. 

 What material progress have we to boast of? What 

 further light have the same instruments, or others of greater 

 powi r, thrown on the minute subdivisions of the n: 

 the abnormal and inexplicable outlines of the shadow of 

 the globe ? On the contrary, with the exception of the ra- 

 dial streaks or notches figured by Trouvelot, the existence 

 of which seems incompatible with the received idea as to 

 the structure and rotation of the rings, how little can be 

 mentioned, traces of which, to say the least, cannot Lie 

 found even in very early records! The brilliant spot 

 detected by Hall seems to have been in some measure 

 anticipated, notwithstanding the inferiority of their in- 

 struments, by Cassini and Fatio nearly 200 years pre- 

 viously. The dusky markings on the ball appear in the 

 rough designs of the elder Herschel, who also noted, for 

 about a week in 1780, a division, possibly not since seen, 

 near the inner edge of one ansa only of the broad ring. 

 The curious striations of the outer ring shown, among 

 others, by the beautiful object-glass at Nice, date back to 



the 6]-inch reflector of Kater in 1825, if not to an earlier 

 instrument of Short's ; while their existence is now un- 

 accountably ignored by the gigantic achromatics of 

 Chicago, Princetown, and Washington ; and other details 

 might be specified, described in earlier days, but not 

 corroborated or referred to now. This is certainly not 

 what might have been expected ; nor is it easy to assign 

 its cause. Instrumental imperfection cannot be alleged : 

 some minute dark markings might possibly be obliterated 

 in telescopes which give large spurious disks ; but this 

 idea is incompatible with the separation of extremely 

 close stars which the modern instruments effect. Irra- 

 diation cannot be supposed to affect perceptibly light of 

 so little intensity as that of Saturn. As far as atmosphere 

 is concerned, we in England might claim many an excuse 

 for failure ; yet Dawes and De la Rue and others would 

 point to results unsurpassed elsewhere, and with no more 

 efficient instrument than a 9j-inch mirror by With I have 

 repeatedly seen Encke's division, while it is imperceptible 

 with far superior means in the purer American sky. " Per- 

 sonal equation'' might be credited with a share in the 

 discrepancies — as, for instance, when on one occasion I 

 missed Enceladus but caught Encke's hair-line at the 

 very time when the reverse was affirmed by the well- 

 trained eye of a friend ; but this would be far from cover- 

 ing the whole amount of difference. It remains, therefore, 

 to be seen whether any further advance can be made by 

 sharper, or more widely diffused, or more persistent 

 scrutiny. We wait for further intelligence. We have 

 not heard how far the most remarkable investigations of 

 Bond and his associates at Harvard have been substan- 

 tiated by the same instrument in the hands of their *ur- 

 cessors.' Something might be looked for at Greenwich 

 from the ready comparison of the workmanship of Merz 

 and Lassell. Few tidings have reached us from the acute 

 research of Schiaparelli ; no results from the splendid 

 Roman sky. A greater mass of evidence might be 

 brought to bear upon debateable points, and, in the pre- 

 sent state of science, may reasonably be expected. 



But even in an improved position as to information we 

 might find a difficulty in interpreting discordant evidence, 

 and deducing from it a consistent conclusion. At present 

 we may incline to the idea that we must take refuge in an 

 actual change of dimensions, or position, or brightness 

 in some of the details. But, even if this would explain 

 more than it will do, we are at a loss as to the possible 

 cause of such changes. 



The great difficulty which confronts us is our entire 

 ignorance of the real nature of our object. A certain 

 degree of previous acquaintance with what is before us 

 may in some cases tend to preoccupy the judgment, but 

 in others it assists in clearing the way. We are seldom 

 puzzled in interpreting the aspect of the moon, because 

 we arc persuaded of its general solidity and fixity. But 

 what is it that we gaze upon in Saturn ? Analogy, often 

 so valuable an assistant, breaks down here. A magni- 

 ficent globe is set before us, but how little can we guess 

 its constitution ! One step would be gained if its density 

 at all resembled our own ; but there we are thrown out at 

 once. We simply cannot imagine a state of things so 

 utterly unlike our own experience, or draw any reliable 

 conclusions from what we see. We may safely infer that 

 the surface of the globe is chiefly shrouded in vapour in 

 which currents ascend or descend according to their tem- 

 perature, and are swept by different times of rotation into 

 longitudinal streaks. And we may further suppose that 

 the atmosphere is of no great comparative depth from the 

 occasional presence of less uniform variations in form and 

 shading, such as would not be compatible with any great 

 difference of velocity between the highest and lowest 

 strata. But as to what may lie beneath, not a conjecture 

 is available ; nor do we knew that it is ever exposed to 

 tin- 1 ye. We may assume that the globe is warmer than 

 surrounding space or such alternating currents would rol 



