246 



KNOWLEDGE 



[Sept. 19, 1884. 



I entirely apree with you in holding that the possessor of " vague 

 notions" about how birds fly is not likely to lead to good results in 

 aerostatics, and you will doubtless agree with me in thinking that 

 very precise and correct notions on that subject might well be 

 invaluable. 



It is obvious that every notion in regard to flying now the pro- 

 perty of man has been derived from the birds. Had it not been 

 for the flapping birds no one would ever have adopted the notion of 

 using active force, such as muscular, steam, or any other known to 

 us, to urge his way into the unresisting air. 



This was done by Darwin in the book above quoted ; and it is a 

 constant astonishment to me that no Englishman has seen the sig- 

 nificance of his ob.servations, and, as a consequence, placed the 

 human race in the air. 



The condor is a strong bird, some fifteen feet in nlar dimensions, 

 weighing twenty pounds, and having a stomach capiieity for five 

 pounds of carrion. Darwin says it cannot flap itself off of the 

 ground, bnt has to run into the air ; and if surprised before having 

 time to indulge in a short foot-race, is easily captured. 



What chance, then, is there for a man to flap himself into success 

 when the best specialised animal extant in this direction is unable 

 to do it ? Man has no specialisation in that direction, and weighs 

 four times as much. 



Darwin goes on to say that this bird, once in the air, moves with 

 astonishing grace and ease, traversing the air at will in any direc- 

 tion, without flapping at all ! He is emphatic on the point of 

 rigidity of pinions, and I submit that, coupling these two facts, 

 they far outweigh in value all experiments tried by man in this 

 field. 



For they show that with the large, heavy birds " flapping," or, 

 in other words, active force, is not a factor in flight, and the whole 

 question is shifted to other grounds, and the usual conception of 

 " flying" completely changed. It becomes possible, with the light 

 thus shed upon the problem, to throw it into a proposition of 

 general terms, which may be thus stated : — 



Flight is the result of the distribution of weight and position in 

 relation to atmospheric air. If Darwin has rightly stated the facts, 

 that is about the state of the case. Active force is eliminated. 

 So far as the bird is concerned, it simply does notlang, and for 

 doing nothiru/ a man is as admirably sjiecialised as any creature on 

 earth. Whatever bugs, bees, and beetles may do in the way of 

 flapping — however humraing-birds. tomtits, kestrels, kites, and 

 other small fry manage to get about— is beside the question. There 

 is nothing discoverable about them which man may hope to 

 imitate. But if Darwin is right, there most surely is about a 

 condor, and because he so clearly observed and recorded these 

 facts, I suggest that you should have admitted him into the circle 

 of the promoters of aerostatics. 



Every item of advance mentioned which may buttress hopes for 

 successful flight is fully anticipated by this English naturalist fifty 

 years ago. He pointed out that a body weighing 251b., with a 

 certain distribution of weight in given dimensions, is sustained in 

 air, and translated in any direction, with or against the wind, and 

 in opposition to gravity, without the employment of any active 

 force whatever. 'Tis true that this fact needs an explanation. But 

 bear in mind that an explanation is all that it does need. The /act, 

 there is no doubt about, and why the experts of a country able to 

 produce a Darwin have not long ago supplied that explanation is 

 humiliating. J. Lancaster. 



Chicago. 



MIND AXD BRAIN. 



[1404] — In reference to the assertion of Professor Biichner, in 

 "Force and Matter," that the molecular change or vibration in the 

 brain, which accompanies every thought, is thought itself, I venture 

 to ask the following question : — What is the power which determines 

 the nature of such molecular changes ; compellinfj the brain itself, 

 by what we call an effort of will, without the aid of the association 

 of ideas, to evolve, at one instant, a thought (e.g.) respecting 

 theology ; at the next, one in classics or mathematics ; at a third 

 attempt, on some wholly different subject. Must there not, in fact, 

 be some controlling power, distinct from the brain itself, which uses 

 the brain as its instrument in the production of thought, and thus 

 effect f the molecular changes ? 



To me it appears indisputable that Professor Biichner mistakes 

 effect for cause. S. F. B. Peppix, Yicar of Herrington. 



[Mr. Peppin's is a query so pertinent that I insert his letter at 

 length. — Ed.] 



SHOOTING STAES. 



[14-05]— I see by Letter No. 1389 of your issue of the 12th inst., 

 Mr. W. H. S. Monck thinks that certain shooting stars, after 

 vaporisation in our atmosphere, may solidify again outside it, while 



others may pass through it, without being reduced to meteoric 

 dust. Further, that these bodies may, in future, revolve round the 

 earth as a centre, instead of round the sun. If such be the cas**, 

 and if Saturn's rings consist of an infinite number of small satellites, 

 the earth, I take it, would by this time be provided with a eimiler 

 appendage, visible to man, unless the myriads of meteors so re- 

 volving, which must have accumulated in the course of ages, could 

 be present without reflecting light. If this be impossible, the in- 

 ference is, I submit, that none escape disintegration, or, if they d<s 

 their orbits are not so affected as to make them play the part of 

 satellites to our planet. Eve- Witness. 



SHIPS' LIGHTS. 



[1406] — Having lately commenced to take Knowledge, in 

 monthly parts (I am sorry I d'd not commence sooner) I read with 

 much pleasure your able article headed " Sent to the Bottom." 



1 have hundreds of times felt keenly what you say in that article, 

 viz., that the present system of signals at sea tells little or nothing 

 even when they are seen, and they ought to be so arranged as iti 

 tell us everything that can be told by signals about the position 

 of ships and the courses they stand upon. 



Going along among a lot of vessels, steam and sail, going in diffe- 

 rent directions in daylight ^ we can thread our way easily as long us 

 every one keeps the steering rules, because we can see exactly which 

 way every vessel in sight is heading, but the moment darkness sets 

 in uncertainty "reigns supreme," although the weathermay be clear 

 enough for us to see all the lights within our limits. Many a timo 

 in crowded waters I have stood on deck the whole night with my 

 teeth set, and my heart in my month most of the time — especially 

 when I had charge of a sailing vessel — where I had not the power 

 to stop and reverse, seeing a number of lights about me which tohl 

 me but a mere fraction of what was necessary for me to know, in 

 order to go along safely. 



If those at the head of affairs were to torn their attention to 

 such matters as these, their praiseworthy efforts to diminish the 

 loss of life at sea would, in my humble opinion, be crowned with 

 more success than any other way they can take. Let them, by 

 legislature or otherwise, give us ships so constructed and equipped 

 as to give us a fair chance to avoid danger, and the instinct of self- 

 preservation will do the rest. 



It is, indeed, surjjrising, as yon say, that matters are allowed to 

 proceed for a single month without change. 



Your plan, in my opinion, is so simple, that any one with brains 

 enough to make him fit to take charge of a vessel for a " watch " 

 can master it in half-an-hour, and the sooner the present system is 

 unlearned the better. M. P. 



S.S. Prydam, Aug. 3, 1884. 



PRINCE KRAPOTKINE'S CAT. 



[1407] — The question being to what extent a cat is affected by 

 her reflection in a mirror, Prince Krapotkine writes to the Revue 

 Scientifique that his cat of fourteen months old, which he has 

 reared during his imprisonment, when he perceives his image evt-n 

 in a hand-glass, will assume a serious air and endeavour to touch it 

 with his paw. Then, meeting the surface of the mirror, he makes 

 for the back of it, evidently fancying another cat is behind a pane 

 of ordinary glass. If the mirror be withdrawn he will follow it up 

 until he assures himself there really is no other cat behind ; aiid 

 then he walks off, and will pay the matter no further attention. 

 This cat does not mew to have the door opened, but stands on his 

 hind legs, and shakes the latch with his fore-paws. He knows the 

 prison-bells, such as those for rising in the morning, and the various 

 meals. When the well-known prisoner takes his evening walk up 

 and down his room, the cat goes through all sorts of antics, ami 

 makes a lot of little purring noises to obtain a game of hide-and- 

 seek, with which he is not pleased unless his master takes hi.'* 

 turn in hiding too. He understands a few words. When he wants 

 to play with his string, if asked, " What do you want ? Food ? A 

 drink?" (manger, loirf,) he gets huffed and walks away ; but the 

 moment the word " string " (ficelle) is pronounced, he makes two 

 little sounds which clearly mean "Yes." J. O'N. 



RAILWAY ACCIDENTS. 



[1408] — I have read with very great interest the valuable details 

 relating to continuous brakes and railway accidents which have 

 appeared in your columns, and I am extremely glad to see this im- 

 portant subject so fully discussed. There is no doubt that the 

 general public does not understand the most important point in the 

 whole matter. The usual opinion appears to be that "a brake 

 must be a good train-stopper." The fact is, an efficient continuous 



