SCIENCE NOTES.

Otago Witness, Issue 2258, 10 June 1897, Page 48

SCIENCE NOTES.

*.• Ther6 are now at least sis kinds of new raya before the public, assuming the X rays to be one kind only. First come the cathode rays, existing inside an exhausted bulb placed in the path of aa elsctiris discharge, and demonstrated long ago by Crookes, Hittorf, and others. Then we have Lenard'e rays, which are cithode rays that have escaped from a bulb by means of an aluminum window. These ray 3 are eensitive to magnetic action, and can be deflected by a magnet. They will also act on a photographic plate through maty opaque substances. Rontgen rays exist in combination vrith Lecard's rays, but are not deflectable by a msgn&t, aad possess more pronounced powers of " photographing the invisible." The rayons uranigues or phosphorescent rays discovered by H. Eecquerel are given off by uranium and its salts, and are also capable of acting on a photographic plate. These rays were independently discovered by Professor Sylvanu3 P. Thompson, and differ from Rontgan rays, as they can be both refracted and polarised. Then come the glowworm's rays, which have recently bean shown by Dawson Turner and by a Japanese investigator to have a faint pbofccgraphic action through aluminum and through coppsr. Finally, there are the rays emitted by phosphorus, which will penetrate black paper, but not aluminum. There are still possibilities of other undiscovered rays existing within the compass of the Oroofees tube, Professor Thompson having shown that daring the coarse of exhausting a bulb, before the Rontgen rays make their appearance, some other rays appear which differ from the cathode or Lenard rays, inasmuch as they are electrostatically as well as magnetically sensitive. Photographs taken without the direct rays of the sun, or without the X rayp, or any electric apparatus whatever, ara something entirely new. This has been done by Mr H. M. Rjdd, city engineer, in some experiments he has been making. Hs first exposed some common granulated white sugar to the sun for two bours. Then, on an ordinary photographer's plate, in an ordinary frame, he placed several coins. Qvev this he placed a white eak board an inch thick. On this be spread a layer of the sugar, one-eighth of an inch thick. He covered half of tho surface with a book toeeeif any difference would be made in the sides of the plate. The whole was placed in an ordinary room for 48 hours. The plate was then developed and a negative printed. The centre coin, an old-fashioned copper, was reproduced perfectly, head, Btars, and date, in exact detail, and very plainly. The other coins were fainter. • . • The close scrutiny to which the planet Mars is being subjected through telescopes at various observatories on the earth's surface might prove embarrassing to the inhabitants of tbat planet were they aware of the facb. There are no limits to our inquisitive.ness except those of space and human capabilities. -Several accomplished astronomers have been watching the changing features of the planet's surface, and although they have of late discovered nothing of startling interest they are gradually accumulating valuable information on matters of detail. Professor Schiaparolli has lately published the interesting observations he has made on the planet. The observer saw 31 canals appear in 1881 and 1882, and only 18 of these were observed in 18S8 and 1884, while seven new ones wera noted. Across the polar area in the later years was seen a large dark rift which divided the enow which lies there through the Martian winter into two unequal portions. Last year another observer, Herr Leo Brenner, was able to distinguish in all 126 canals. Of these 13 were previously noted by Lowell and 82 by Schiaparelli. He claims to have seen five new seas. These are blue-green areas some hundreds of square

miles in extent. Herr Brenner saw the last of the south polar snow on Si-ptember 8. The rapidity with which the polar snowcap disappears leads astronomers to think that it is a comparatively thin ono. Most of tho observers diU'er in their rendering of what they see on the planet's surface. Their ob- | servations, too, differ in some respects ; a fact which is partiy due the difference of the telescopic power at thair command, and partly to the " personal equation " which snterginto almost every scientific observation. • . • Lieutenant Baden-Powell contributes to the United Service Magazine for April a paper entitled '• The Conquest of the Air," the object of which is to show that aerial navigation is now no more a wild dream, but will very probably form a prominent feature of the next great war. Ha describes Mftxim's machine, and then turns to another, that of Mr Phillips, which ia propelled by a screw driven by a steam engine. It weighs over 3001b, but although, when it is set going at; the rate of 30 miles an hour, it rises a few feeb in the air, it seldom remains more than a lew seconds. The Kaiser has given £2500 towards experiments in thia direction, and it is scientifically demonstrated on psper that aerial flight is posßible. He says that Captain Kenard'rf balloon, with the lifting power of 85001b, driven by a gas engine of 45 tons power, has travelled at the rate of 25 miles in the air. A large navigable balloon is now being made in Germany, and the Kassfans have been at work for some years at a very large balloon. Efficient machines of many descriptions conld probably be made straight off if only we could turn out a suitable light motor. The Power that first di&covers how to make this motor will probably be able to keep ifc a secret: — "Within a few hours of the declaration of war some aeromotives could be despatched, high ouh of range of guns, and perhaps travelling acsuch a speed as to ensure safety from projectiles, over the enemy's country. From them explosive shells could .be dropped where and when the aeronauts willed. By thia means not oaly could fortifications be damaged, magazines blown up, ships sunk, and towns attacked, bufc also railways and telegrapfaio communication could be interrupted, bridges and tunnels rendered useless, troops on the march dispersed, guns and stores destroyed, and, in short, all attempts to carry on war utterly disorganised. Would ifc not then sa«m madness to attempt a war against a nation possesaieg even a few such machines, if we ourselves had none 1 " Lieutenant Baden-Powell says that a nation with a few efficient aerial motor* could almost be without any army or even navy. Ha calls for a committee of experts to inquire into the matter, and urges that ships must ba fitted with horizonal armour and guns made capable of firing upward. • . ♦ The penetrating powers and ranges of powerful lights, such aa are employed ia lighthouse service, rapidly decrease aa the ratio of their luminous powsr increases. For instance, a light of 5,000,000 candle power in the British Channel has in average weather a luminous range of about 44 nautical miles, whjlsif the light be increased to the power of 10,000,000 candle the luminous range is only five mjles more, or 49 miles. According to current practice, lights up to 200,000-candle power are obtairsed by means of mineral oil lamps, while electric lights are used for higher powere, and almost any power may thus be obtained. The highest power aa yet attempted is about 36,000,000, afc Penrnark Point, in the dopartment of Fiaisterre, France, which, when completed, will be the most powerful* lighthouse illumination in the world. The height oE the tower in which ifc ia to bs located is about 63 metres, enabling it to be sesn during the day from a distance of 18 miles in fine weather. Daring the night this light will be visible for GO miles. The rotundity of the earth will prevent the rays from striking the eye directly at a distance of more than 30 miles, but the sky overhead will appear illuminated for 30 miles more. The estimated cost is about 120,000d0l. — Machinery. • . •An inquiring scientist has made a peculiarly interesting report on tho results of a long study of the various kinds of fear to which children are subject. It seems that thunder and lightning cauao terror to more children than any other one thing 1 , and following in the order named come reptile*, darkness, fire, deatb, domestic animals, disease, wild animals, water, ghosts, insects, rata and mice, robbers, and high winds. Ifc is pleasant to notice that the fear of ghosts comes very low on the list. ■ . •No one will ever determine, to the satisfaction of everybody concerned, who invented the telephone ; but the authorities at Washington, U.S.A., decided that Alexander Graham Bell had a right to the patent, and, as a result of that decision, Mr Bell has become a millionaire. The inventor, however, is indebted to other causes besides the Patent Office for his wealth. Had he not fortunately foucd a backer in his wife's father, Mr Gardiner G. Hnbbard, who possessed considerable means, the telephone might have brought him little or no reward. Miss Hobbard, by the way, who became Mrs i Bsll, was a deaf mute, and for her sake ] her husband has devoted a great deal of time and thought to the relief of her fellow j sufferers. He devised a'system of lip-reading by means of which he taught his wife to converse, and which has been widely adopted I by others. i • . • A remarkable accident took place recently at Calais. A large boiler was being carried through the streets upon a trolley drawn by a team of 16 horses, when the metallic mass came into contact with some overhead electric light wires and broke them. These broken wires caugfafc on to the boiler and the framework of the truck, with the result that the current was conveyed to the horses and knocked them all senseless, gome of them being killed. Toe men in attendance also received savere shocks.

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