516 



♦ KNOWLEDGE ♦ 



[Dzc. 2G, 1834. 



coincidence by which a comet — discovered in that very 

 year 18G6 — was found to travel in precisely the same 

 orbit which had thus been assigned to the meteor-system. 

 Already astronomers had suspected the existence of a con- 

 nection of some sort between comets and meteors. Schia- 

 parelli had shown that it the August meteors follow in the 

 track of the conspicuous comet of 1862, which passed 

 very near the part of her orbit traversed by the earth on 

 Aug. 10, their paths would seem to radiate, aa they 

 actually do, from a point in the constellation Perseus. Bat 

 this might have been a mere coincidence. The agreement 

 between the 7;«</ts of the November meteor-system and 

 Tempel's comet (Comet I., 1866) was a very different 

 matter. If the garrison in a beleaguered city found 

 several cannon-balls falling on the same place and from 

 the same direction, they might guess that these had all 

 come from the same ' gun — but they could not be certain. 

 If, however, they could determine the exact trajectories of 

 two of these bodies, and found them exactly alike, they 

 could no longer doubt that the same cannon had projected 

 them. Now the exact paths of the November meteor- 

 system and of Tempel's comet have been determined, and 

 are found to be the same (within the narrow limits of 

 errors of observation) : no doubt then can exist that the 

 meteors and the comet have had the same origin. The 

 same has since been shown in the case of other comets and 

 other meteor -systems. 



It has been customary to repeat Schiaparelli's explanation 

 of this peculiarity, — that a flight of meteoric bodies ap- 

 proaching the solar system after a journey from interstellar 

 .space, had chanced to approach so near one of the giant 

 planets as to be diverted from its original course to an 

 elliptical path around the sun, the path always thereafter 

 intersecting the orbit of the disturbing planet. Slight dif- 

 ferences in the velocities thus assigned to the meteors 

 would account, said Schiaparelli, for the gradual trailing 

 of many of the meteors behind the main body. This main 

 body would be the comet, the laggards would be the 

 meteoric train (this train being entirely distinct it 

 will be understood from the comet's tail, indeed 

 T,empel's comet had no tail worth mentioning). 

 Sthiaparelli's theory was accepted by some astronomers 

 well able to have examined it effectively, without 

 sufficient inquiry. For it is in truth altogether untenable. 

 It can be shown in the first place that a meteor -flight would 

 have to approach a planet much more closely than is at all 

 likely, to have its path changed in the necessary degree. 

 But what is more important, it can be shown that if a meteor- 

 'flight did approach a planet thus closely its various members 

 would be very differently affected, and so would be spread 

 into a scattered, widely-ranging flight altogether unlike the 

 ^,existent meteor-streams. There is curious evidence, I may 

 '.' y;ei3Qark in passing, of the carelessness with which Schiapa- 

 .'r'elli's explanation was accepted. Even astronomers of 

 V rgpute have repeated the statement that those meteors 

 which were most delayed as the flight passed the disturbing 

 p.l£ynet would lag behind the rest. As a matter of fact 

 those which were least delayed would be the laggards, par- 

 doxical though it may sound to say so. If our earth were 

 checked in her course so as to lose a considerable part of 

 her velocity she would complete her next circuit round the 

 sun in a much shorter period (it would of course be much 

 diminished in extent), i.e., she would return ahead of time: 

 but if she were hastened in her course she would be much 

 longer in completing her next circuit. Nay, if the earth's 

 actual velocity of about 18 miles per second were increased 

 to 25}j miles per second she would never complete another 

 circuit, the range of her path being increased infinitely. 

 So with the meteors of Schiaperelli's imagined flights, those 



most delayed would come back soonest to the place where 

 they had been disturbed, and be ahead of their fellows. 



But we need not consider minor flaws in a theory which 

 is in truth entirely untenable. 



To replace this unquestionably erroneous theory respect- 

 ing the common origin of comets and meteors by a true 

 one, would not be easy. The probability is that we have 

 to look back into depths of time .so remote that we can hope 

 for no clear view of the processes by which comets and 

 meteors came into existence. I must confess I see little 

 hope in that outlook into interstellar space to which 

 Schiaparelli, Hoek, and others have invited us. It seems 

 to me far more likely that comets and meteors have, for 

 the most part, belonged to our system since it began to be, 

 than that they have been gathered in from that vast un- 

 known region which separates our sun from his fellows. 

 I imagine that comets and meteors are either the " frag- 

 ments that remain " from the vast mass of nebulous matter 

 or cosmic dust out of which the solar system was gradually 

 formed, — or else they had their origin from the various orbs 

 forming that system when as yet those orbs were in the 

 sunlike state. Only one member of the solar system 

 is now in that state — the sun himself ; though the 

 giant planets retain more sunlike characteristics than 

 many imagine. Now the sun does unquestionably eject 

 matter from his interior from time to time, with ve- 

 locities sufficing to carry such matter for ever away from 

 him : he has been caught in the act Again, the micro- 

 scopic examination and the chemical analysis of certain 

 meteors have agreed in showing that these bodies were 

 once aggregations of liquid globules in a hydrogen atmo- 

 sphere of considerable density — or, as Sorby the minera- 

 logist and Graham the chemist agree in putting the matter 

 these bodies once existed under conditions such as belong 

 only to sunlike bodies. If the sun still gives birth to 

 meteor-flights, one can see no reason why the giant planets, 

 ivhen they were suns, should not have done likewise : but, 

 on the contrary, strong reason to believe they would have 

 done so. The comet families of the giant families travel 

 on orbits indicating such an origin, and a flight of meteoric 

 bodies ejected from Uranus millions of years ago, would 

 travel on precisely such an orbit as that of the November 

 meteors. Such seems to me the most reasonable interpre- 

 tation of the facts, and the one most consonant with all 

 the evidence we have. 



< 



RAMBLES WITH A HAMMER. 



OVER CHAENWOOD FOREST. 

 By W. Jerome Harrisox, F.G.S. 



CHARNWOOD FOREST ! How many of my readers 

 know the place? Perhaps there are some who do 

 not even recognise the name. And yet Charnwood occu- 

 pies thirty square miles in the very heart of England. 

 Look for it in the north-west corner of Leicestershire. 

 There lies the craggy region of old rocks — between 

 Leicester and Loughborough on the east and Ashby- 

 de-la-Zouch on the west, with the Trent running alongits 

 northern base — which it is my purpose now to describe. 

 The very came tells us of the nature of the district — 

 " Quern-wood," the w^ood whence hard stones suitable for 

 the querns or old hand-mills in which corn was ground could 

 be obtained. The hard stone is there still, but the trees 

 are nearly all gone. In Bradgate Park the picturesque, 

 stunted, bossy oaks still flourish, but, as for the rest of the 

 " forest," the fatal Enclosure Act, which came into opera- 

 tion la 1829, has destroyed much of its wildness and 



