Feb. 1, 1886,] 



♦ KNO\VLEDGE ♦ 



125 



Satum, Uranus, or Neptune. Near, too, as the 

 approach is now, we may reasonably assume that 

 this nearness of approach indicates actual intersec- 

 tion at some remote time in the past. The resem- 

 blance between this peculiarity, and the intersection 

 of earth - ejected meteor - si reams with the earth's 

 orbit, according to the theory of Tschermak and the 

 Astronomer Royal for Ireland, need hardly be insisted 

 on. If, as they consider almost certain, the meteor clouds 

 vomited forth bj^ the earth iu long-past ages became 

 meteor streams travelling round the sun, but always 

 passing near the earth's orbit, then the more important 

 meteor clouds expelled by the giant planets would 

 become more important meteor systems travelling round 

 the sun, but ever thereafter passing near the track of the 

 planets from which they had severally been expelled. 

 And, in one case as in the other, the meteor stream 

 would imply a comet, for we have every reason to infer, 

 from what we know about meteors and comets, that 

 every meteor system is probably associated with a comet. 

 Indeed, two of the meteor systems actuallj' identified as 

 attendants on comets, follow severally in the tracks of 

 comets belonging to the families of the giant planets 

 — the meteors of November 14 following in tfhe track of 

 Tempel's comet which passes very near the orbit of 

 Uranus, and the meteors of November 27 following the 

 track of Biela's comet which passes very near the orbit 

 of Jupiter. 



I am fully aware that another explanation — only one 

 other seems even possible — has been suggested for the 

 strange way in which contets and meteor systems cling 

 around the orbits of the planets. This other explanation 

 has even been sometimes described — though qtiite 

 erroneously — as the accepted theory. It was advanced 

 by Schiaparelli as an adjunct of the theory — which 

 really has been accepted, because demonstrated — that 

 meteors and comets are associated. He suggested that 

 the meteor systems which now pass near the paths of 

 the giant planets may have been drawn into the solar 

 system by the perttirbing action of those planets near 

 which, on their parabolic coru'se around the sun, they 

 chanced to pass. But while this explanaticm gives no 

 account whatever of the structitre of meteoric bodies, 

 it even fails to account for meteoric streams as we 

 know them. It has been shown (with mathematical 

 demonstration) that no flight of meteors could ever, by 

 the attractions of a giant planet, be so perturbed that all 

 its members would thenceforth travel on practically the 

 same orbit round the sun. Those passing nearest to the 

 distttrbing planet would inevitably be sent off on a 

 different path from those which were in the middle of 

 the approaching flight, and these on a different path from 

 those farthest away, unless the flight were very small 

 indeed, in which case its members would be kept together 

 by their mutual attractions and no meteoric stream would 

 be produced. 



On the other hand, the theory I have advanced, while 

 itself stiggested, and almost demonstrated, by a priori 

 evidence, explains perfectly the structure of meteors, and 

 accotmts for the eventual conversion of a flight of meteors 

 (vomited forth in the form of a meteoric cloud in some 

 immense eruption) into a meteoric stream. 



But we cannot stop here. There is a test which this 

 theory, if sound, ought assuredly to bear. There are 

 orbs actually in the sunlike stage — to wit the stars, and 

 our own star (the sun) in particular. These ought to be 

 acttially doing what we have found such strong reason 

 for believing that our earth did in the remote past, and 

 the giant planets (still in the youth of their much longer 



lives) did, not so very long ago. They ought to be 

 ejecting occasionally vast flights of meteoric masses from 

 their interiors. Our sun, no doubt — to take him as an 

 example — would have to eject such masses with far 

 greater energy than the earth mttst have employed during 

 her sunlike youth, to send them beyond his own control. 

 For whereas seven miles per second would have sufliced 

 in the earth's case, 382 miles per second would have been 

 required in the sun's. But then the sun is 327,000 times 

 as massive, and therefore as mighty, as the earth, and no 

 doubt volcanic ejections resulting from that vast strength 

 would, in adequate degree, surpass all that our earth 

 could have done, even in thefulnessof her youthfitl energy. 



We turn our telescopes, then, on the sun to see 

 whether he ever does such amazing expulsive work as 

 this requires of him, perhaps hardly expecting to find 

 signs of it. But lo ! he has been detected in the very 

 act. He has been caught ejecting flights of bodies from 

 his interior with velocities so great that not even his 

 mighty attractive power could ever bring them back 

 again. In one such outburst velocities of 450 miles per 

 second at his visible surface were indicated, which would 

 be 68 miles per second more than would be required to 

 take such matter for ever away from him. This evidence 

 would in reality suflice if it stood alone to account for all 

 the meteoric phenomena we have been dealing with. If 

 he does this now he must have done the like during all 

 the millions of years of his past existence as recorded on 

 the tablets of the earth's crust. If our sun does this, so 

 must his fellow suns, the stars, and they also during 

 millions of past years. Billions of billions of billions of 

 stm-expelled bodies must therefore be travelling in 

 multitudinous courses through interstellar space. And 

 from this we can reason back to the very theory of 

 planetary and terrestrial ejection of meteors to which we 

 had been already led, and from which we had reasoned 

 on to solar ejections. 



This theory of the volcanic origin of meteors, and 

 therefore of comets — for without comets there are 

 jjrobably no meteors, and without meteors no comets — is 

 singularly confirmed by the microscopic and chemical 

 examination of meteorites. For Mr. Sorby long since 

 (1864) announced that the microscopic structure of some 

 meteorites revealed their past existence in the form of 

 clouds of globules of molten metal, a state in which, as 

 he said, they could not have ever existed except in the 

 interior of a body like our sun; while in 1867, Professor 

 Graham, exhaitsting the air around the Lenarto meteor, 

 heated to redness, found hydrogen coming forth in such 

 quantities as to show that that meteorite had " brought 

 to tis across the interstellar depths the hydrogen of some 

 fixed star " — which could have happened no otherwise 

 than throtigh expulsion. 



Meteorites, meteor-streams, and comets would appear, 

 then, to be products of expulsion from suns, from giant 

 planets, and from orbs like our earth when in the sunlike 

 state. — Times. 



BAD TIMES.* 



IHE interpretation given by Mr. "Wallace to 

 the prevailing depression of trade is too 

 near the truth to be so popular as any of 

 the various opposing theories over which 

 party politicians have contended. He 

 goes to the root of the matter : it is a far 

 more popular plan to strike at symjjtoms. 



* •■ r.ad 1 imcs : an essay on the present depression of trade, tracing 

 it to its sources in enormous foreign loans, excessive war expend!- 



