HA RD WICKE'S S CIENCE- G OS SIP. 



147 



glimpse of these strange objects, so very like planets in 

 transitu. A number of them, some five or six, group 

 themselves round a particular day in the month of 

 March or October, in such a manner as to render it 

 possible, at least, that they might be transits of the 

 same body, for it is to be remarked that a transit of a 

 planet can only be seen when the object is near one 

 of the nodes of its orbit, that is, when it is crossing 

 the ecliptic, and thus can only have place when the 

 earth is in the same longitude as the node, or twice a 

 year at an interval of six months. But now the diffi- 

 culties begin to accumulate. If these five or six obser- 

 vations of spots be really transits of a single planet, it 

 should be possible to predict the recurrence of like 

 transits, and Leverrier, believing in the trustworthi- 

 ness of five of them, did predict a transit of Vulcan for 

 the month of March 1877. The supposed planet, 

 however, failed to put in an appearance, and Leverrier 

 died while the question was still unsettled. 



Somewhat later M. Oppolzer has taken up the 

 subject, and using eight observations of spots made at 

 various times during the present century as bond fide 

 transits of Vulcan, found that these could be reconciled 

 by a second hypothesis differing considerably from 

 Leverrier's, and which could readily be tested, as 

 transits must occur very frequently, and he fixed the 

 18th March of the present year as one of these crucial 

 occasions. Just as previously, however, astronomers 

 in all parts of the world anxiously scanned the sun 

 upon the day named, and met with the same ill-success. 

 Probably this would have been the last attempt of the 

 kind, and astronomers would have remained content 

 with this negative evidence as proving the non-exist- 

 ence of Vulcan, but the question in the meantime had 

 assumed a new phase. 



We have stated that Vulcan should be visible in 

 all probability to the naked eye, and certainly with 

 the aid of small telescopic power during a total 

 eclipse of the sun. Frequently as these phenomena 

 have been observed of late years by the most ex- 

 perienced astronomers, none have glimpsed the 

 doubtful Vulcan, although in justice it must be said 

 that these precious moments have generally been 

 fully occupied by the investigation of a variety of 

 other important questions. As these, however, have 

 gradually neared to a solution, the last total eclipse 

 visible in America in July 1878 was devoted by several 

 able astronomers to this task, and the search for 

 Vulcan was perhaps the most prominent feature of 

 the observation. Two of the observers alone claim 

 to have seen planetary bodies near the sun, though 

 perhaps in consequence of the haste in which their 

 respective positions were noted it has not been found 

 possible to identify and reconcile the remarks of the 

 two discoverers, so that whether there were one or 

 two or three or four Vulcans seen during the eclipse 

 is regarded by some as an open question. One point, 

 however, is conceded, viz., that none of the four can 

 possibly be the theoretical Vulcan of Leverrier, nor 



the inferred planet of Oppolzer, and we are thus 

 afforded valuable evidence that the cause of the 

 erratic movements of Mercury has not been discovered, 

 and in all probability is not discoverable in the shape 

 of a planet nearer to the sun than it. 



It would be useless, however, to deny that much 

 interest attaches to what was actually seen in America 

 last year, and it is with a certain amount of relief 

 that we find the examination of the observations then 

 made has been taken in hand by so eminently able a 

 mathematician as Dr. C. H. F. Peters, and a result 

 evolved that admits of no cavil. He has shown to 

 the satisfaction doubtless of all unprejudiced persons 

 that the discoverers were themselves mistaken, and 

 had fallen into the error of taking conspicuous stars 

 to be minute planetary bodies, and without impugning 

 either their ability or their honesty, the excitement 

 and hurry of the moment are amply sufficient to 

 account for the erroneous announcement which startled 

 the world a few months since. At the very moment 

 when the believers in Vulcan thought they had their 

 hands on the object of their search have their hopes 

 been dashed to the ground ; and as if to crush the 

 last lingering remains of life entirely out of this hope- 

 ful hypothesis the same astronomer has been able to 

 show incontrovertibly that the most trusted observa- 

 tion of the supposed planet on the solar disk is utterly 

 unreliable. It is seldom that so fatal a stroke has 

 been aimed at a long-cherished scientific fallacy. 



But it must not be forgotten that the change of 

 position of the axis of Mercury's orbit is an ascertained 

 fact and needs explanation. We require continually 

 to improve by observation the data upon which our 

 theoretical results are based, and should it be found, 

 as there is already some ground for believing it may 

 be, that the planet Venus is a denser and more 

 powerfully attracting body than it has hitherto had 

 the credit of being, the difficulty will be solved, and 

 the theory of gravitation will stand in as proud a 

 position as it could have done had the conjectures of 

 Leverrier been confirmed by the discovery he so 

 ardently longed for. 



ON THE STUDY OF INFLORESCENCE. 

 By H. W. Syers, B.A. Cantab. 



THE consideration of the manner in which flowers 

 are arranged on the axis which bears them is 

 a very interesting and a very important division of 

 botanical study. Not only do we find that flowers, in 

 their position and arrangements, are far from occupy- 

 ing merely haphazard and chance positions, but, on 

 the contrary, in all cases the arrangement follows 

 such simple and definite forms, that systematic 

 botanists have found the inflorescence or antitaxis a 

 most valuable assistance and guide in classification. 

 The study of inflorescence teaches us not only the 

 relative positions of the flowers to each other and to 



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