418 



• KNOWLEDGE 



[Mat 15, 1885. 



it) must admit their share in the highest humanities; and 

 ■whirit is true of them is true, to a (jreater or less extent, of 

 animals generally. Yet shall we, bf-cause wc walk on our 

 hind feet, ussume to ourselves only the privilege of im- 

 perishability'! Shall we, who are ev^en as they, though we 

 wag our tongues and not our tails, demand a special Provi- 

 dence and a selti-h s^alvation 1 



Lewes (laughing) — Buchanan, like all young men, is an 

 ■optimist ! His spiritual scheme embraces every form of 

 existence, as well as the whole human race. 



George Eliot-^And why, even, the whole human race 1 

 Go into the slums aniJ dens of the city, visit our prisons 

 and inspect our criminals, not to speak of the inmates of 

 our lunatic asylums ; and what do you find 1 Beasts in 

 human likeness, monsters with appetites and instincts, often 

 even the cleverness, of men and women. Are these 

 immortal s-ouls too, independent of physical limitations, 

 and journeying to an eternal Home ? 



Myself — Certainly. There is no form of humanity, 

 however degraded, which is beyond the possibility of moral 

 regeneration. 



Lewes — Optimism wiih a vengeance ! Optimism which 

 leaves out of sight all the great physical factors of 

 Euoral condact — hereditary disease, cerebral malformations, 

 thought-perverting congestions, all theeidless ills that flesh 

 is heir to. I'm afraid, after all, that the dream of a per- 

 sonal immortality is a selfish one. It would come, in the 

 long run, merely to the survival of the fittest, who would 

 build their heavenly mansion on a hecatomb of human 



failure But there, we've talked enough of things at 



present in.«crutable. Come out into the garden, and soothe 

 your mechanism with a cigar. 



We left the Sybil to her meditations, and walked out 

 into the open air. As we strolled smoking along the garden 

 walks, we heard faintly, as from a distance, the murmur of 

 the great city. 



"Do you really believe," I .<;aid presently, "that the 

 divine thought of Shakespeare was a mere secretion, and 

 that the last word of Science iwill be one of sheer negation 

 and di-spair ? " 



He looked at me thoughtfully, then watched the 

 wreaths of smoke as they curled from his mouth up into 

 the air. 



" Man is predoomed to aspiration, as the smoke flies 

 upward. The last word of Science will not be spoken for 

 many a century yet. Who can guess what it will be ] " 



FLIGHT OF THE BUZZARD. 



DURING my visit to the Southern States of America, I have 

 bad several opportunities of watching, under favourable con- 

 ditions, the flight of the buzzard, the scavenger of Southern cities. 

 Although in most res'pects this bird's manner of flight resembles 

 that of the various sea-birds which I have often watched for hours 

 sailing steadily after ocean steamships, yet, being a land bird, the 

 buzzard is more apt to give examples of that kind of flight in which 

 a bird remains long over the same place. Instead of sailing steadily 

 on upon outstretched pinions, the buzzard often ascends in a series 

 of spirals, or descends along a similar course. I have not been able 

 to tiu;e the continuance of the longest flights during which the 

 wings have not once been flapped, for the simple reason that, in 

 every case which I have attempted to do so. the bird has passed 

 oat of view either by upward or horizontal travelling. But I am 

 satisfied that in many cases the bird sweeps onwards or about on 

 unflapping wings for more than half an hour. 



Now, many treat this problem of aijrial flotation as if it were 

 of the nature of a miracle — something not to be explained. Ex- 

 planations which have been advanced have, it ia true, been in many 

 cases altogether unt- nable. For instance, some have asserted that 

 the albatross, the condor, and other birds which float for a long 

 time without moving their wings, — and that, too, in some cases, at 

 greai heights above the sea-level, where the air is very thin— are 



supported by some gas within the hollow parts of their bones, as 

 the balloon is supported by the hydrogen within it. The an.=wer to 

 this is that a balloon is not supported by the hydrogen within it, 

 but by the surrounding air, and in jast such degree as the 

 air is displaced by the lighter gas. The air around a bird 

 is only displaced by the bird's volume, and the pressure 

 of the air corresponding to this displacement is not equi- 

 valent to more than one five-hundredth part of the bird's weight. 

 Another idea is that when a bird seems to be floating on 

 nnmoving wings there is really a rapid fluttering of the feathers of 

 the wings, by which a sustaining power is obtained. But no one 

 who knows anything of the anatomy of the bird will adopt this 

 idea for an instant, and no one who has ever watched with a good 

 field-glass a floating bird of the albatross or buzzard kind will 

 suppose they are fluttering their feathers in this way, even though 

 he should be utterly ignorant of the anatomy of the wings. More- 

 over, anyone acquainted with the laws of dynamics will know that 

 there would be tremendous loss of power in the fluttering move- 

 ment imagined as compared with the effect of sweeping downwards 

 and backwards the whole of each wing. 



There is only one possible way of explaining the floating power 

 of birds, and that is by associating it with the rapid motion acquired 

 originally by wing-flapping, and afterwards husbanded, so to speak, 

 by absolutely perfect adjustment and balancing. To this the answer 

 is often advanced that it implies ignorance of the laws of dynamics 

 to suppose that rapid advance can affect the rate of falling, as is 

 implied by the theory that it enables the bird to float. Xow, as a 

 matter of fact, a slight slope of the wings would nndonbtedly pro- 

 duce a raising power, and so an answer is at once obtained to this 

 objection. But I venture to assert, with the utmost confifience, 

 that a perfectly horizontal plane, advancing swiftly in a horizontal 

 direction at first, will not sink as quickly, or anything like as 

 quickly, as a similar plane let fall from a position of rest. A 

 cannon-ball, rushing horizontally from the mouth of a cannon, 

 begins to fall just as if it were simply dropped. But the case of a 

 horizontal plane is altogether different. If rapidly advancing, it 

 passes continually over still air; if simply let fall, the air beneath 

 it yields, and presently currents are set up which facilitate the 

 descent of the fiat body ; but there is no time to set up these aerial 

 movements as the flat body passes rapidly over still air. 



As a matter of fact, we know that this difference exists, from the 

 diilerence in the observed behaviour of a flat card set flying hori- 

 zontally through the air, and a similar card held horizontally and 

 then allowed to fall. 



I believe the whole mystery of aerial flotation lies here, and that 

 as soon as aerial floating-machines are planned on this system, it 

 will be found that the problem of aerial transit — though presenting 

 still many diflienlties of detail — is, nevertheless, perfectly soluble. — 

 E. A. Proctoe, in Newcastle Weekly Chronicle. 



A SUGGESTION has been made for the establishment of a British 

 Textile Institute. Any one desirous of co-operating in such esta- 

 blishment, either by becoming a member of the Institute or other- 

 wise, may communicate with Mr. Ashenhurst, of the Bradford 

 Technical College, who will supply all needful information. 



Ox Tuesday, 5th inst., Mr. C. V. Boys gave a lecture at the Royal 

 Victoria Hall, Waterloo Bridge-road, on " Light and Colour." 

 Colour was shown to be a property, not of coloured bodies, but of 

 the light by which we see them. This was provt-d by a row of 

 papers, coloured when seen by magnesium light, but appearing 

 black or grey by the light of the yf How sodium flame. Various 

 dyes, indistinguishable from each other or from ink by this yellow 

 light, were used for painting on a white screen. The gas was then 

 turned up. and bright colours became visible. The next step was to 

 produce a spectrum by bending aside a beam of white light with a 

 prism. To show that there was no colouring matter in the prism, 

 white light was reproduced by bending the beam back to its 

 original direction with a second prism. The eiiect of red glass in 

 stopping the green rays, and of green glass in stopping red rays 

 was shown, darkness being caused by passing the beam through 

 both glasses. The action of the colours used in painting is like this : 

 they reflect to the eye coloured light because they have robbed the 

 white light which fell on them of one of its constituents. Thus we 

 get black by mixing paints of all colours together. When, however, 

 we mix, not paints, but coloured lights, so that one light is added 

 to another without anything being destroyed, we get white. This 

 was done by rotating a disc with coloured sectors, so that before one 

 colour had time to fade from a given part of the retina, another 

 colour was presented to it. The result was that the disc appeared 

 white. Mr. Boys wound up by showing the effect on coloured 

 objects of various brilliant monochromatic lights. 



