SCIENCF NOTES. !

Otago Witness, Issue 2572, 1 July 1903, Page 80

SCIENCF NOTES. !

—An interesting article on "Human Flight" appears in the new number of the Edinburgh Review, in which we have a comparative study of the most reoent attempts to effeot tb© conquest of the air. Notwithstanding popular opinion, the labours of M. Santos-Dumont and other inventors of navigable balloons have really nothing to io with the sclutiou. To bo able to travel through the air against the v/ind a speed of at least 50 miles an hour must be attained, and the wind pressure on any form of balloon or "air ship" a-t such » speed would instantly reduce it to a wreck. A ten-mile speed like that attained in the famous trip round the- Eiffel Tower as nothing to the purpose. Really to fly w« must imitate- the soaring of birds themselves. Darwin noticed that the condor eoared on it& .mt-spread wings without the flapping, collapsing its winga if it .(wished to fall, and then spreading them and

veing the impetus gained in the- descent to lisa again. Professor Langley has the 'aremairkabld discovery that with a body imjpelted forward on "aeroplanes," or artificial wings, the faster the movement the less power needed to maintain it. An aeroplane travelling at 25 miles an hour will support

151b per horse-power, so that one of our „ lightest motors, weighing 71b to the horsepower, would barely, keep up in the air double its own weight. But it a speed of

4-5 miles, with the aeioplane almost horizontal, one horse-power would euppoflt 2091b. , The striking contrast between the navigable IbaJlooii" and the flying machine is that, .■while speed ie impossible with the former, with the flying machine the greater speed the less friction and the greater the weight transported by a given power. The flying machine — or kit© driven by a motor — is the solution of the problem, and not tho balloon. £bo greater its speed the greater tho economy of working, and when the problem of starting and stopping has been solved t we may easily have such incredible speeds as u> hundred and fifty or two hundred mil^e an horn. Sir Hiram Maxim has already constructed an aeroplane that will fly, but ffor the present thingß are it a deadlock .until someone tells us how to start and alight. Now, the one thing nced'nl for tfchis purpose ie knowledge and skill in •(balancing. As Mr H. G. Wells has pointed out. the balance required in kating or icyoling m quite bewildering: to the beginner. Infinitely more difficult will be the balance required for flight — the instantaneous adiustment of the wings, the quick response to a passing breeze, the swift recovery of equilibrium, the giddy, eddying movement* that require such absolute preoision. Science La, done almost all it can for the moment;

sport must be responsible for the n.ext step.

— Why do plantf grow upward? Most of ■us would say that they stow towards the light. But the light explanation does not cover the ground, else in thi* latitude- all the tree* in the open fields would bow northward toward the sun. The •uprightness of trees and plants, an immensely useful quality, must have some -oUier cause. Mr Francis Darwin, in a lecture to tho Royal Society, has been giving the results of pome interesting experiments on the subject, dealing with the question why the plant grows •upward and the roots down In the tips 'of the roots of certain loedhnps it wap found there were special cells, each containing a free starch grain, which naturally 6ank to the bottom, and changed ii f s position if thf> plant were laid on it* side. The staroh |rrain, always repponding to the earth's klownwaird attraction, keeps thp plant Informed of which direction is up anJ which down, and co applies a stimulus determining growth in a vertical direction. Mr Darwin tried plants laid on their sides, and stimulated by a sidelight, but still they grew upward. "When +he plants were placed on a vibrating surface, so that the starch grains tapped on the 'bottoms of their cells, tho uward curvature of the growth wa« increased, tJie gravitational stimulus being made more active. The fact that the gravitational apparatus is situated in certain tiefinite regions, such as the root-tip, where it is required to determine tb« direction of growth, sueirests that it belong*. Mr Darwin cays, to "that type of physiolo^icel mac-hhip •which we call a penrp-oriran." Wo shall cay mow that plant" live but do n^t fcol' — For some time tho. C4rrat 'Wrsteru RailTcay Company, with a \ icw f o securing; the finest locomotive power pc^ible for the ■working of thf ir "C'ornishrmn" and oM or ]ong-di*tancp e-tprf^fv, have bppn innuinng into the merits of t 1 o keomnd\p« of "ther countries, not excepting Anipvira. mvl arrangements wore last venr "omplrted for th© experimental introduction of on^ of thp ©slebrated De frl'-hn compound, winch pro tised vrith such conspicuous success on tho

Nord railway of France in hauling their express traffic between Pane and Calais and Lis-le resncciively. This engine is now neanng completion at the works of the Societe Ateaciennes dcs Constructions Mecmiques at Belfort, France". At the works of the Great We-stern railway at Swindon the newly-appointed locomotive superintendent of the Great Western railway h*><s designed and completed a new outside cylinder exprc«»3 locomotive, which is stated to Le ths largest in this country, and mark? the limit in height and width available on English railways. It was at first proposed that the De Glehn engine for the Great Western railway ehould be erected at the Swindon works, but the directors of the English railway wer© resolved that the experiments ehould not be complicated by questions of workmanship, material, or erection ; the intension being to test a real Fren-ch locomotive on an English railway. In order that it may be seen whether these "compounds" or the latest type- of eng-'eie just completed at the Swindon works is the most suitable, French driver* and firemen will b& lent by Mons. dv Bousquet, engineer of the Nord railway of France, to work the De Glehn engine, whilst, if necessary, even French briquettes will be imported.

— Professor Spring, the well-knoivn scLentist, has examined the commonly-accepted theory advanced by Hagenbach, that the blue colour of the sky is diie to the refraction of light caused by solid or liquid particles floating in the air. In laboratory experiments the author never succeeded in obtaining the blue colour, the reflected rays of light always showing either red, y-ellow, or violet. Purification in no oa^e removed the blue tint from the air. After exhausting all physical means in ?n attempt to reproduce the blue colour, the author concluded that the blue of the sky depends upon ehemioal conditions. The colour deepens instead of fades a« the observer rises above tTie earth. These conclusions are Eiupported by the faot that liquid air is also blue.

—It is a matter of very common knowledge that when a lighted candle is. placed in a confined air space t ! :e flame is &ocmer or later extinguished. Whether, however, this extinction is due to the combustion products of the candle — that is to say, chiefly to the carbonic acid gas — or to the removal of oxygen has not very long been decided with any d&gree of certainty (says the Lancsi). Certain it is that the flam© of a candle or of a match goes out when the oxygen is dim nished to ,a point below 17 per cent. It would b& impossible to kleep a match alight in an atmosphere containing much less oxygen than this. The extinction of the flame, however, is due not to the addition of carbonic acid gas, but to the depletion of oxygen. It may bo a source of consolation to some people to know, when they aie mi fear of being suffocated in a ■railway carriage or railway runnel, that life is poe*:ble ac long as the tobacco in a pipe or cigar burn, or to long as the smoker ib able to keep a match alight. — Notwithstanding that the sun is our all in all, we know but little of its history and constitution. True, we have learned pome things. Science has weighed tho mighty sphere, and found it 300,000 times a° heavy as our earth ; we have m&asuicd the .«un, ccid ascertained that its bulk is more than one and a-quarfcet million times greater than that of the globe we inhabit: we know that the eun revolves at a distance of about 93,000,000 miles from, us, and that many of the elements familiar to us assist in its composition. An ordinary telescope shows that the surface of the sun is marked in places with small dark snots. These enots. which were discovered in 1611 by Fabricus, Galileo, and Soheiner, aro continually undergoing a rapid .pi-occ;s of change of conformation, and often disappear altogether. Sir Robert Ball said, some years aao : — "It cannot be Tgardod as proved that the sun spots .ire. really depressions in th< v surface ; indeed, many astronrinipr* hold different views on tl.e subject " Tlie dai'k central region of a spot is a cavity. This is eprtam where tho fpot is of a circular appearance, and docs not vary mi' oh in sliap". In 1858 a soot w?« scon with a diameter of 144,000 square mile.? — a hole "which wou'il have contained, a hundred splnrrr.s each as large as the earth. Tl is ifi Hie Lirgpst sun spot on record. There is oon c ideiable ac*i\ity at the preeent time in the ?uu Various spots have rccntly appeared, fc'ic. greatest of which is 20,000 milps in diameter. To sun spots may bo attributed the discovery that the sun revolves completely m its axis In a period of about 25 or 26 days. This was proved by the way in which «-potis were carried onward day aftor day towards thp sun's edge, tlierp to vanish from view until they re-ap-]>e-a.rcd on th^ op)>rMte odee. Run .'ixits am iioti permanent: ihpy fado as mapioallv as tl pv ari^f. and dr mons'i-ate that the c iin'.s %i = ible siirfaof' is a romjlomeration of blazing or ■\aporous matter. Frequently a prot divide?, and the par's rvFh from each o^her at the rato of 10CO ri'ilos an hour. The earth's macmeti.-m is generally in a violent state of disturbance whpn the spots ore most prevalent. But this is not always the cise. The neriod of Uip reourl*cnoe of a maximum number of =un spots is on an nveraee a, little over 11 vrars. This has bepn the case for the last 3PO vea.r.= Spots npver occur in the Polar i-K>ffior« of the ran, but only on the zones on each side of tho Equator. — Liverpool Post.

Old winter comes with chilly breath, Unnging sicklies*, sometimes death ; Yet e\cry family, piaise the paints, May now be fiee from client complaints. At "winter's cold and winter's rain Wo can liu<rh with might and main, For w" l'T\o t'>f» remedy pure — W. E. W oodo' Great PtrrEiiMixi Cube.