CORRESPONDENCE. 



MARS. 



To the Editors of " Knowledge." 



Sirs, — In your issue of June there appeared on the above 

 subject a letter, signed J. E. Maxwell, which contains so many 

 errors and misrepresentations that their complete refutation 

 seems to me necessary. 



In the first place there is a confusion in the very purpose 

 of that paper, since its author chiefly disagrees with me on an 

 idea of mine which he himself adopts. It is stated in my 

 article, on pages 193-196, that although there are no straight 

 lines on Mars, yet this truth would not be accepted without 

 opposition, and that the astronomer of the future will sneer 

 at these wonders. Hence I made it quite clear that my 

 arguments and proofs had not yet secured public recognition, 

 and that, consequently, at present they are not established 

 truths. Yet the author of the letter in question, in his anxiety 

 to contradict, overlooks that he appropriates my idea by 

 proclaiming that my views " are not established truths." But 

 even otherwise considered, the argument has no bearing ; for 

 when an investigator is sure that he enunciates the truth, he 

 cannot but remain utterly indifferent to the acceptance, or 

 temporary non-acceptance, of his results by the public. 



The correspondent in question next says that he has never 

 before seen it stated that " canals " appear " straight and not 

 curved at the edge of the disc." And yet canals are drawn 

 straight near the limb by Schiaparelli, Perrotin, Terby, Guiot, 

 Wilson, Cerulli, Lowell, Douglass, and others. Further, 

 from one of the numerous papers in which this peculiarity was 

 pointed out, I shall quote a passage in " Knowledge " for 

 1894, page 250, where we find that "the 'canals' when near 

 the edge of the disc are apt to be represented as much 

 straighter than they could possibly be." With ordinary care 

 and prudence such public display of unaquaintance with the 

 subject treated could easily have been avoided. 



Another glaring oversight is the assertion that "no markings 

 . . . can be seen near the limb of Mars, owing obviously to 

 the planet's atmosphere." That this is just the reverse of 

 reality is proved by the photographs, which show all dark 

 markings quite as intense near the limb as near the centre of 

 the disc. The apparent character of the bright limb, due to 

 contrast with the dark sky, is naturally not even suspected 

 here. 



There is nothing extraordinary in the fact that Mr. Denning 

 discovered the true nature of the minor detail on Mars with 

 a ten-inch, while Mr. Lowell failed to do so " with his twenty- 

 four-inch." For, to say nothing of the superior ability and 

 experience of the former of these two observers, the effective 

 difference between their telescopes is not the difference of 

 ten and twenty-four, as erroneously pointed out on pages 

 238, 239, but the difference between ten inches and thirteen 

 and a half inches, since this last is the usual aperture to 

 which the twenty-four-inch is stopped down on Mars. 



The writer of the letter quoted next fails to understand the 

 effect of magnification of a planetary disc on the sharpness of 

 its markings. Yet nothing can be clearer. Inasmuch as the 

 fine lines flashing on Mars are usually flashing on a disc 

 having the apparent size of a sixpenny piece held at the 

 distance of two feet from the eye, they ought to be represented 

 quite sharp on such a small disc held at the above distance. 

 But on a three-inch drawing, seen at one foot, the sharpness 

 would cease, just as the sixpenny piece enlarged photographic- 

 ally to six inches would show nothing but very vague details. 

 Should further corroboration be needed on this point, it could 

 be found on the best photographs of Mars, which, while 

 revealing more delicate detail than any ever drawn prior to 

 1909, yet show all markings diffuse on a disc smaller than one 

 inch in diameter. 



On page 239 doubt is cast on the fact that the narrow 

 straight lines on Mars are seen only by glimpses. Here, 



again, we have a confusion of the straight fine lines with the 

 diffused streaks, held steadily. My experience, like that of 

 Terby and others, is that the lines are always flashing for a 

 small fraction of a second ; and as this was also Schiaparelli's 

 experience, I shall be excused if I accord a greater weight to 

 the Martian observations of Schiaparelli than to those of an 

 unknown amateur. 



With regard to Figures 190 to 193, page 194, we are now 

 asked to believe that the structure of the planet was 

 geometrical and furrowed with straight lines on 1909, 

 September 18th; that it was natural and irregular, without 

 lines, two days later, on September 20th, and also on 

 October 5th ; and that it was again geometrical with straight 

 lines on November 3rd. The manifest impossibility of such 

 an assumption proves that my drawing, corroborated, as it is 

 by Professor Hale's wonderful photograph, shows Mars 

 practically as he is (so far as our present optical means go), 

 and that the rude sketches of Mr. Lowell and M. Jarry- 

 Desloges, which fail to reveal the coarser details, break down 

 altogether under the crucial and unanswerable test of photo- 

 graphic comparison. Behind the impersonal confirmation of 

 photography, I am awaiting all critics with a smile ; and the 

 overwhelming superiority of large telescopes, displayed every 

 day on double stars, and by the spurious satellite to Sirius 

 discovered at Mr. Lowell's observatory, thus receives an 

 additional, though useless, corroboration. 



I granted some years ago, and still grant, that Flag- 

 staff may enjoy the finest atmospheric conditions for 

 astronomy. But as the aperture there is some thirteen and 

 a half inches, Mars is defined in Arizona as if he were from 

 two and a half to three times more distant than in the three 

 largest refractors of the world. This is the reason for which 

 a few seconds of perfect seeing at Yerkes, Lick, Meudon, or 

 Mount Wilson have done more for the recognition of the true 

 character of the Martian spots than the laborious canal 

 records of nine whole apparitions at Flagstaff. Does the 

 correspondent know that the areographer who drew more 

 straight lines on Mars than any other — Professor A. E. 

 Douglass— in a visit paid me in 1910, declared all the canals 

 which he was seeing for years with Professor Lowell's very 

 telescope at Flagstaff to be illusive. 



Discussions on such a one-sided affair as the canal 

 question are, of course, useless. Yet the present letter, besides 

 refuting opposition, has also rendered clear the position of 

 the believers in the linear canals, which is : (a) that, 

 within certain limits, the more distant a heavenly body is 

 from the observer, the better he distinguishes the details of 

 its surface ; (b) that, within wide limits, the greater the 

 confusion of vision of an object, the sharper its perception ; 

 and (c) that the laws of perspective, on which our knowledge 

 of the universe stands, are wrong. 



When the defenders of a theory are reduced to question 



the truth of natural law for its support they merely betray 



the rout of their reasoning. 



E. M. ANTONIADI. 

 Paris. 



HEN BIRDS WITH MALE PLUMAGE. 

 To the Editors of " Knowledge." 



Sirs, — Regarding the statement by your correspondent (the 

 Director of Melbourne Zoological Gardens) that hen-pheasants 

 and so on, assume the plumage of the male bird under certain 

 conditions, it may interest your readers to know that when 

 visiting Folkestone Museum a few years ago I saw there a 

 stuffed specimen of a cockerel which a card near explained 

 had formerly worn hen plumage, and even laid eggs. The 

 bird had been the property of a farmer in the vicinity whose 

 name is attached to the card. 



A. ATKINSON. 



Harrogate. 



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