78 



KNOWLEDGE. 



March, 1915. 



In the opening passages of this article I mentioned 

 the philosophic significance of abstractions to be 

 drawn from a consideration of the facts about Mars. 

 It occurs to me that some might be led to the idea 

 that I have pursued my investigations in regard to 

 the canals with a \aew to pro\ang their objectivity 

 and artificiality. As a matter of fact, although 

 such considerations should have no effect one way 

 or the other, I uill confess that, if anything, they 

 influenced me primarily to incline toward the views 

 of Lowell's antagonists, so fearful was I of being 

 led into a belief in conclusions influenced by their 

 desirability. Also the objective existence of the 

 " canals " seemed too romantic to be true. My object 

 in mentioning the philosophic aspect was to impress 

 upon readers the supreme interest and importance 



of the canal question, and also to suggest an 

 explanation of the fact that the theory has met 

 with such \'iolent and, in some cases, unreasonable 

 opposition. 



There are some who, accepting Lowell's observ- 

 ations as accurate, endeavour to show that the 

 " canals " might have originated in some natural 

 manner. Space does not permit me to discuss these 

 views in this article. Suffice it to say that the abso- 

 lute directness with which these objects run, accord- 

 ing to Lowell's drawings, their obviously economic 

 arrangement, the progressive changes which take 

 place along an individual canal after the melting 

 of one of the polar caps, and a thousand other 

 details admit of absolutely no other explanation 

 than that they are of artificial origin. 



NOTES. 



ASTRONOMY. 



By A. C. D. Crommelin. B.A., D.Sc, F.R.A.S. 



METEOR ORBITS.— A few years ago I referred to 

 a paper on this subject by Mr. Charles P. Olivier. He has 

 just pubhshed a second paper (PubUcations of Leander 

 McCormick Observatory, II, 4). The results are based on 

 two thousand eight hundred meteors observed in 1911, 

 1912, and 1913. His main principle is that meteors used for 

 deducing radiants must all be observed on the same night. 

 He gives one hundred and twenty-six parabohc orbits of 

 meteors, which, with his previous list, brings his total up 

 to three hundred and two. These are not all different 

 showers. Many refer to the same shower on different 

 nights or in different years. 



He reviews the growth of our knowledge with regard to 

 the connection of the May Aquarids with Halley's Comet. 

 This was suspected by Falb in 1868, further discussed by 

 Professor A. S. Herschel in 1876, and by INIr. Denning not 

 long after. But he claims to have been the first to make 

 the connection a moral certainty. The meteors have 

 suffered great dispersion, both along the orbit and at right 

 angles to it. The former is shown by the display in 1913 

 being nearly as great as in 1910 ; the latter by the fact that 

 some of the tracks are eleven million miles from the comet's 

 track. Observers are asked to pay special attention to 

 these May meteors in coming years. 'The fact that they are 

 observ'able only in the small hours considerably reduces 

 the number of watchers. It is conjectured that the'Orionids, 

 visible in October, may also be offshoots of Halley's Comet, 

 which makes a fairly close approach to the Earth's orbit 

 at both its nodes. The evidence, however, is much less 

 decisive than in the case of the Aquarids, and it is necessary 

 to postulate much wider dispersion from the parent orbit. 



Mr. Ohvier considers that the Orionid radiant shows 

 a distinct shift among the stars on successive nights, and 

 gives the following figures : — 



No. of 

 Date. G.M.T. R.A. N. Dec. Meteors. 



d O D 



1911, Oct 17-72 ... 89-1 ... 16-3 ... 3 



1912 18-02 ... 88-8 ... 15-0 ... 5 



1911 19-77 ... 92-8 ... 13-0 ... 13 



23-78 ... 96-9 ... 14-5 ... 3 



, 23-80 ... 92-6 ... 15-7 ... 13 



24-80 ... 95-5 ... 16-5 ... 10 



25-76 ... 97-8 ... 14-4 ... 10 



The R.A. seems to increase 1° daily, the declination 

 remaining constant. This was one of the radiants that had 

 been described as " stationarv', " so the discovery of its 

 motion is of special interest. 



The table of the number of meteors of various magnitudes 

 is also interesting. Out of 2229 meteors 90 are of mag- 

 nitude 0, or brighter; 167 of magnitude 1 ; 318 of mag- 

 nitude 2 ; 537 of magnitude 3 ; 730 of magnitude 4 ; 323 

 of magnitude 5 ; 51 of magnitude 6 ; 13 fainter than 6. 

 There is a steady increase up to magnitude 4. The falling 

 off after this is probably due to the greater difficulty of 

 observation, not to actual scarcity of the fainter meteors. 



The August Perseids are noted as having been very 

 numerous in 1907 and 1910. 



There is a note on the effect of the passage of a large 

 meteor on telescopic vision. On 1911, May 17th, Mr. Latimer 

 J. Wilson was observing Jupiter, the seeing being perfect. 

 A large meteor passed 35' above Jupiter. Immediately 

 after its passage the upper atmosphere was so violently 

 agitated that only the coarsest features of Jupiter could 

 be seen. The oscillations lasted four or five minutes, 

 gradually dying down. 



From the long hst of meteor orbits I select a few that 

 show an unusually close approach to the Sun. The quantity 

 q denotes the perihelion distance. 



Radiant. 

 Date. R.A. Dec. q 



July 



Oct. 

 Nov. 

 Dec. 

 Dec. 



31 



19 



2 



9 



344-2-11-6 0-010 



53-5-f22-4 0-019 



65-l-fl6-5 0-069 



107-8-f25-9 0-032 



9 1270 + 17-1 



0-018 



THE PLANETESIMAL HYPOTHESIS (Continued).— 

 There are four possible courses for the matter leaving 

 our Sun under the action of the other Sun : — 



(1) Some of the matter returned to the Sun. 



(2) Some described elliptical orbits round it. 



(3) Some may have been driven into hyperbolic or para- 



bolic orbits. This would be lost to both systems. 



(4) (a) Some may have been captured by the other Sun, 



and described elliptic orbits round it ; (b) con- 

 versely some of the other Sun's matter may have 

 been annexed by our system. 

 The further development of the theory deals only with 

 (2) and (4) (b). The matter" takes the form of a spiral with 

 two streams issuing opposite one another, . . . nearly in 



