SCIENCE NOTES.

Otago Witness, Issue 2929, 4 May 1910, Page 76

SCIENCE NOTES.

A Thousand-day Clock.— This latest production of the horologists' art is~ a distinct departure from the clock that everyone is acquainted with. It has neither pendulum, tick, nor escapement. The motive power is a smaU electric battery, which actuates a magnet, which control* the very few and simple works that the dock contains. One battery will run the clock for a thousand days, and when run down it is only necessary to replace the Ibattery. —A New Speed Indicator. — An instrument has been invented by Mr Thomas Farrow (of Farrow Bank, Ltd.) for use on motor cars. 'it is designed to be fixed on the front of a car to indi- ■ »te in bold letters the speed at which, the vehicle is travelling. Immediately the speed limit of. 20 miles an hour has been exceeded a gong is sounded and continues to ring until the speed is reduced. The device" is illuminated at night by an electric- lamp, while in addition to the figures. ' shown »in a forward direction another set is visible to the driver and occupants of ■ iho car. The Ophthalmodiaphanoscope. — The ophthalmp-diaphanoscope of Dr Carl Efertzell, of Berlin, lights the retina (the ecreen—inside —at the back of the eyeball) from the back, so that the oculibfc can examine the interior of the patient's eye much more effectively than is possible by the use of an eye-mirror and reflected light. An electrio lamp—which may have as high as •30 candle-power—is held in the mouth to give the illumination. The lamp is kept Cool by a water-jacket, a small elevated l tank supplying the cooling lirjuid through a flexible tube, and the heated Fater from the lamp escaping through a waste pipe. A : little alarm lamp lights up when the tank jhas been emptied and needs refilling. The 'examination of the eye must be made in a dark room, and a- black mask over the ■patient's face shuts out the illumination of the front of the head that would interfere the operator's work. ; —Music-charmed Water.— Interesting experiments showing the influence of a tuning fork on jets of water liave been made at the Royal College of Science in Dublin. A jet of falling water consists ordinarily of two parts, a clear jolumD and a troubled portion. When the troubled part is photographed frith the aid of electricity it is seen to be cc-aiposed of a succession of drops following one another too rapidly to be separately perceived by the eye. These drops are irregular in ■ize, shape, and distance. But if a vibrating tuning fork is placed in contact with the stand > from which the jet starts the drops fall into order with beautiful precision, a drop being cast off with each vibration. Many remarkable afects can thus be produced. A continuous jet may be thrown into a form like that of a yibrating string. The Power of the Camera. — . " 'Just as there are sound waves which are too small and vibrate too quickly to make themselves heard by the hu&oan ear, ro there are light waves which are too minute to be perceived by the human eye. In other words, we might say that there were pome kinds of light too piercing to be seen. But what the eye cannot see there are instruments which will record, and the photographic plate can see light which man cannot. Many uses have been made of |hat. Some of the wonderful spiral nebulae »£ the sky have photographed themselves pn the plate by their own light, and so nave revealed themselves as man never hoped to see them. But that is not all. 3Ch© photographic plate which thus has enabled man to see the immensely great may' .help him to see the. incredibly small. It will render him the same kind of service that it has done 'in looking at the field of the telescope—it will make them clearer, and it will show their structure. -7 Smoking and Disease.— Smokers will be delighted to learn that a military doctor has discovered, and undertakes to prove by convincing statistics, that light smoking, instead of being bad, is good for the health. Better still, smokers are almost immune from meningitis. Tobacco, ' therefore, instead of being tabooed by 6ome joaedical men, ought to be hailed with delight, and anyone threatened with -the terrible brain or spinal attack should be at once told to take the nicotine cure. The discoverer of this new scientific fact is Dr de Kermabon, of the French army. He has patiently gathered statistics and watched the ravages of cerebro-spinal diseases among the young - recruits o f the OFrench army, and as their habits, among others that of smoking, are carefully noted in the reports, he was astonished to see that so few of the habitual smokers were attacked by the disease. The proportion. ' as established by him is 1 1 1> 20 —that is to say, for one case of meningitis among " % given number of smokers there are 20 eses of the disease among an equal numx of non-smokers. Electric Giants for Mountain Trains. — Giant electric locomotives are now shut--1 ling trains back and forth through the < wo-milo tunnel of the Great Northern I Trunk line railroad, which pierces the '. Cascade Mountains about 100 miles east of »jeattle, U.S.A. The mammoth locomotives { rere built by the General Electric Company t f Schenectady, N.Y., weigh 230,0001 b each, t'evelop more than 2000 continuous horselower, • and are capable of delivering a traction effort of 80,0001 b. The use of electric locomotives entirely eliminates the dangerous smoke and gases which frequently overpowered engine-drivers and trainmen, imperilled the lives of passengers, and gaeatly delayed traffic. The big electrics are capable of hauling the heaviest trains, steam, locomotives and all, up the steep gradea which were impossible for steam looomc tives except those of the largest kind. .. , ..■ ! Mathematicians and Flying ■■-■■ -■"■..• Machines:— '- : -; " Mathematicians have always told us,"' says Sir Hiram Maxim, " that a flying machine would be possible just as soon as a suitable motor for the purpose was discovered. For this remarkable motor we are indebted to those who have spent hundreds of thousands of pounds in the development of motor oars, ei.i-. :ially those of the racing type. . . . The domestic

[ goose weighs 121 b, and is able to fly, and ; it is said that in doing so she develops the twelith part of a horse-power. Gaso- : line motors have already been made that develop one horse-power for every 41b oi weight—or, say, one horse-power with the weight of a small barnyard fowl, and I find that there is a possibility of reducing this weight to about 2|lb, providing that all the parts are made of high-grade and care-fully-tempered steel. Many philosophers have maintained, and with reason, that if mankind was ever to master the air it would in the very nature of things be necessary to imitate Nature's flying machines—birds—and depend altogether J upon dynamic energy instead of the buoyancy of gas." Problems of the North Pole. — If a man could live at the North Pole through 100 days he would be 100 years old; for a year at the Pol© is made up of just one day and one night. About March 81 the sun peeps above the horizon; but ; not in the east, for to the man on the Pole there is no east, nor west, nor north ; there is nowhere to go but south. A few days later the sun is apparently rolling round on the horizon for the entire 24 hours. Without a timepiece the man at the Pole could not distinguish the 29th day of March from the 30th of March. To paraphrase a popular saying, all days in the calendar look alike to him. The man at the Pole sees all the stars in the northern half of the celestial firmament at one ! time; he has not to wait for the revolution of the earth on its axis to bring any of them into view. But he can never see many of the stars we see. The moon visits the man at the Pole, and keeps him company for weeks, circling the horizon, just as the sun did, but at a lower altitude. The north star, Polaris, is almost directly overhead —it is a degree and a fraction out of true north. At the Pole all meridians of longitude meet; so to describe one's position there no longitude is necessary—only latitude 90deg'. The north pole of the compass points south at the (magnetic) North Pole; so indeed does the south pole of the compass, for south is the only direction away from the Pole. The stars appear brighter, a star of one magnitude less than can be seen by us being easily visible, in the Arctic regions. No rotation of the earth takes place at the Pole. So, if Mr Man was on the equator, ho would be turning with the earth at. the rate of over a thousand miles an hour, while if at the exact Pole he would not turn at all—or, at most, if he stood stock still for 24- hours he himself would rotate just once. APPEARANCE OF THE EARTH THROUGH A MARTIAN TELESCOPE.

It is not easy for a mere earth-dweller to realise exactly what the appearance of this globe must be to those who are privileged to gaze upon .it from somewhere in space. Maps convey no idea, and since training in "the use of. the globes" is little heard of, neither the imaginative nor the unimaginative person had any means of obtaining a really definite impression of the picture that seas and continents, valleys and mountain ranges must make when they are regarded merely as portions of one vast soneme. FOl 13 years past a wellknown geographer, Mr George R. Gill, has been trying to remedy this defect; and recently he made it possible to judge how far he has succeeded. He opened the lid of a big wooden chest, moved a metal framework on its hinges, put a few " meridians " in position, and clipped them there with an "equator," covered the structure with a wonderful skin on a steel foundation, turned a crank that gave his model its correct inclination to the plane of its motion, and another to impart to it the motion itself. Thus in 10 minutes he had built up a globe big enough to contain a man, surprisingly simple in its internal economy, and scientifically accurate in every detail—even the angle of inclination could not be exceeded except by disregarding the warning of a bell! But the skin, of course, is the thing that. makes it possible to imagine what the world must look like to the Martian —if only the Martian has lenses powerful enough to give Jiim so perfect a view of it. On a steel shell, built up in sections that can be fixed or removed in a moment, the surface of the earth has been built up in papier ma.ohe. The shape of the continents, the proportions of land and water, the diversity of surface, the form of the mountain ranges and the height of every peak, the position and extent of the valleys and the watersheds can all be realised from this great "globe" in a way that has been impossible hitherto. Mount M'Kinley has had to be remodelled certainly, and may require further remodelling still; for, since Dr Cook's "discoveries" were discredited, nobody knows anything definite about it. A mountain range in Tibet has been corrected at the suggestion of Sven Redin, , who describes the treatment of Asia as "perfectly wonderful." And as new discoveries are made they will have to be followed by fui--ther changes. But the globe as it now stands —whether with its " physical " skin on, or with an alternative " political" one —is a beautiful thing; jtnd it promises to transform the geography lesson from a labour to an amusement.