Dec. 2G, 1884.] 



♦ KNOWLEDGE • 



515 



AN iLLUST Skated 



AGAZINE OF SCIENCE 



^JJNLYW0I«)ED-EXACTLYDESCRIBED 



LONDON : FRIDAY, DEC. 26, 1884. 

 Contents op No. 165. 



PAOB 



Comets and Meteors. Bj R. A. 

 Proctor 615 



liamblea with a Hammer. {IUuh.) 

 By W. Jerome Harriaon, F.G.S.. ulO 



Other Worlds than Oure 513 



JUeasant Hours with the Micro- 

 scope. By H. J. Slack 019 



The Gambting Spirit in America. 

 By Richard A. Procor 519 



An Interesting Family. {Ulm.) 

 By David Houston 520 



<lur Two Brains. By Richard A. 

 Proctor 522 



Chapters on Modem Domestic Eco- 

 nomy. VIII 623 



PAGB 



First Star Lessons. With Map. By 



R. A. Proctor 524 



The Racers of the Ses 52t 



Reviews : " Custom and Myth " — 



Some Books on Our Table 52fi 



Miscellanea 529 



Our Inventors' Column 630 



Correspondence : Euchd's Theory 

 of Parallels— Matter— Laplace's 

 *' Nebular Theory" — Curious 

 Sunset — Power of Perception — 

 Letters Received and Short 



Answers 531 



Our Chess Column 533 



Our Whist Column 6ai 



COMETS AND METEORS. 



By Richard A. Proctor. 



rriHERE is a marked contrast between our present know- 

 X ledge respecting meteors and that which astronomers 

 possessed before 1866, when Professor Kewton, of Yale 

 College, announced that the earth would pass through a 

 rich part of a certain meteor-system on the night of the 

 13th-14th November, 1866. I am not here referring to the 

 recognition of the nature of meteors as extra-terrestrial 

 bodies. Too often the credit of this recognition is assigned 

 to the astronomers who, during the last quarter of a century, 

 have done so much to advance our knowledge beyond that 

 point. But, in reality, Professor Olmsted, of Newhaven, 

 Conn., had proved conclusively that meteors are non-telluric 

 bodies, long before the modern school of meteoric astro- 

 nomers had entered on their labours, and to him the whole 

 credit of that part of the work of research must be assigned. 

 His reasoning was perfectly demonstrative, though he did 

 not succeed in convincing many of his contemporaries, or 

 even in attracting their attention in any marked degree. 

 Many in his day followed a custom which is common 

 enough now, and regarded as suggestive of eminent caution 

 and scientific prudence. Carefully avoiding any real 

 expression of opinion, tliey remarked safely that " Prof. 

 Olmsted's reasoning was worthy of careful consideration, 

 though we are far from admitting that the startling theory 

 to which hia reasoning seems to point is a sound one : pos- 

 sibly the facts on which he insists may be explained in 

 some other way." That theory had, however, been in 

 reality demonstrated ; and it now forms part of the basis 

 on which meteoric astronomy stands. 



An outline of his reasoning can be easily and bripfly 

 presented :— The lOth-llth of August and the 13th-14th of 

 November are days on which meteor-showers may be looked 

 for. But a particular day in the year is the time when 

 the earth reaches a particular part of her orbit. Therefore 

 certain parts of our earth's track are, as it were, infested 

 by meteors. Now there is no possible way in which this 

 can be brought about but by the passage of meteors, 

 in flights or systems, across the track of the earth at those 

 particular places. In the striking words of Alexander 

 Humboldtj who (though he was never much of an astro- 



nomer) was keen-sighted enough to see the force of 

 Olmsted's reasoning, which many astronomers overlooked, 

 " the metecirs before their encounter with our earth may 

 be described as ' pocket planets.' " 



The argument needed no clinching, but Olmsted clinched 

 it. He gave another demonstration as perfect as the one 

 he had already supplied : — The falling stars seen during a 

 great display seem to radiate at any given time from a fixed 

 point ; just as parallel lines are foreshortened in perspective 

 to a series of lines radiating from a point. Therefore the 

 tracks of the meteors are parallel. But the point from 

 which the tracks of shooting stars seem to radiate shifts its 

 position from hour to hour with respect to the horizon and 

 the cardinal points. It moves icith the stars and remains 

 stationary among them. Therefore the meteors had been 

 travelling on parallel paths before reaching our atmosphere, 

 and the fiery tracks left by them as they rush through the 

 air form a set of parallel lines difl'erently situated in the 

 air as the earth rotates into different positions, but directed 

 always to the same point on the remote concave of the 

 celestial sphere. 



As a piece of pure reasoning, educing from observed facts 

 their full and true significance, nothing can be more perfect 

 than Olmsted's argument ; the credit of the achievement 

 should not be lightly assigned to others because many 

 careless professional astronomers of Olmsted's day failed 

 to realise the force of his reasoning, or even to pay any 

 attention to it. 



Professor Newton's prediction of the display of Novem- 

 ber 13-14, 1866, started a new series of inquiries. It has 

 always struck me that that prediction was one of the 

 boldest ever made, and (considering the uncertainty which 

 still hangs over all the problems of meteoric astronomy) 

 one of the most fortunate. We know now that the 

 meteors about which he spoke had been 33| years on their 

 course, which carries them far outside the orbit of Uranus, 

 or twenty times our distance from the sun : but in 1866 not 

 even this was known. Professor Newton had a choice of 

 no less than five paths to account for what was then known 

 about the November meteors ; and of all the five the true 

 path seemed to him the least probable. Yet he ventured 

 to predict the time of the earth's transit through the 

 meteor-cloud for the morning hours of November 14, 1866, 

 in the Eastern States of America, and he was not wrong 

 by more than about a quarter of a day, the actual display 

 of falling stars occurring in the morning hours of the 14th 

 in Europe, and being over by the time that the eastern 

 seaboard of America had swung round to the side on which 

 the meteors had been falling. American observers were 

 disappointed so far as the expected shower of falling stars 

 was concerned ; but American astronomers had every 

 reason to be proud of the success of their calculations. 



Science owes to Professor Adams, of Cambridge, the 

 demonstration of the real path of the Leonids, as the 

 November meteors are called (because they seem to radiate 

 from a point in the constellation Leo). By as pretty a 

 piece of mathematical work as has ever been done, he 

 showed that the slight change of position which has been 

 observed during the last few centuries in the crossing-place 

 of the earth and meteors, can only be reconciled with a long 

 oval orbit, 33| years in period, which carries the meteors 

 within the disturbing influences of Jupiter, Saturn, and 

 Uranus. Thus the average interval of rather more than 

 33 years between the great displays of November meteors, 

 is to be explained by the existence of a rich portion — the 

 "gpm of the meteor -ring" it has been prettily called — 

 which returns to the neighbourhood of the earth's orbit 

 once in rather more than 33 years, or about 

 thrice in a century. Then came the singular 



