SCIENCE NOTES.

Otago Witness, Issue 2210, 9 July 1896, Page 48

SCIENCE NOTES.

• . • In the earlier attempts to produce an jncaadesceafc electric light 40 or 50 years ago, the-, slender filament was made of platinum. Edison, Swan, and others subsequently found that carbon bad,eeveral advantages over that substance. ' Its resistance is greater ; less energy is required- to raise its temperature ; and it is practically impossible to melt it, however great the heat. Curiously enough, though, some attempts have recently been made to substitute metals for carbon, but the man (or at least one man) who is trying these experiments employs niobium, tantalum, molybdenum, titanium, and zirconium instead of platinum. These are h)1 known to be exceedingly refractory materials— that is, they are hard to melt. The object sought is greater durability than is possessed by the carbon filament; but the ■wonderful brillancy of the gas-heated Welsbach burners, in which other rare and refractory metals are used (lanthanum, thorium, and praseodymium), suggests the possibility tbafc a brighter light may also be secured in this manner. J. W. Aylswortb, of Newark, N.J., who is among the experimenters, uses a carbon thread for a foundation and coats it with metal,

• . • A m ■ rmd tmexpeotea application of the Ilontgeu rajs is found ia their nee for ascertaiuicg the contents of suspected infernal machines. Professor Brouardel, of the Paris Municipal Laboratory, assisted by Messrs Glrard and Bordae, gave an account of their researches ia this direction at a recent sitting of the Aoademie dcs Sciences, and if their statements on the subject are to be accepted without reservation, it would appear that many of the extraordinary precautions hitherto required in dealing with bombs may now be dispensed with, and the contents of any ordinary infernal machine decided withont risk. The explosive machines experimented with were exactly similar to those which were forwarded some time einco to two prominent defies of the French Ohambar. The mechanism of these was so adjusted that immediately the boxen wen eaenad. tta ex*

plosion occurred. One of these was enclosed in a zinc case, the other in a wooden bos. Ia the first case the experiment was only moderately successful, the impression on the photographic plate only showing an indistinguishable black mass, In the second, however, the contents of the bomb wore clearly manifested, nails, eorews, a revolver cartridge, and even the grains of powder showing plainly.— lndustries and Iron.

',' What is the sixth sense ? Have animals the sixth sense ? When dog*, cats, and other animals are carried in close baskets miles and miles away from their homes and still find their way baok, when carrier pigeons are carried in box^s for long distances away from their cotes and unerringly return, we are inolined to think there is another sense with which animals are gifted, at present unknown to humans.

• . • Everything written or spoken by the antl-vaccinatois has always bad our most careful consideration. Bat although we have tried to be eorupulouely fair, we have never wavered from our conviction that vaccination is magnificently successful, and that aB a matter of veritable and undeniable fact, proved in every part of the world, at all times, ucder all circumstances, and by all Borts and conditions of men, the prophylactic value of vaooination against smallpox is one of those certainties which are so firmly established that they never can bo moved again so long as the world stands.— The Hospital.

'. • An English steamer, the Scandia, wa* recently overtaken by a terrific storm in mid-Atlantic, and the captain, having no store of gil on board which he could throw on the troubled waters, tried the effect of soapsuds, and, it is said, with the greatest success. The effect was instantaneous, the height of the waves being immediately diminished and their crests being less threatening. The captain. of a French vessel is also reported to have employed soap solution with similar success. He need throo kilogrammes of soap dissolved in 70 litres of water, and dropping the mixture over the bowc of his sbip, ensured a quiet pathway for it 10yds wide. 1 • . • Horseless mail waggons will soon be used in all the large cities of the United States. Second Assistant Postmaster-general Neilson has for several months been study ing the project?, and a few days ago completed the plans for the model carriage. It is now in course of construction, and will be completed very soon. The dimensions of this new wnggon will be 12ft long, 6ft wide, and a tri/l-s over 6ft high. It will be fitted np precisely as a mail street oar or a steam railroad postal car, except that the scale will be smaller. The body of the waggon will be bung on springs and counter springs and the wheels shielded with heavy rubber tyres. It has now been definitely settled by the Post Office department to employ the horseless waggons in the transportation of mails in the city and country districts where there are no railway lines and where the service can be improved by making " separation?," assorting the mail between office while ia transit It is intended to pkee these waggons in service in oities which oover a large area, and where "separation" between four or five stations will greatly facilitate mail delivery.

• . •In a recent communication to the French Academy of Sciences, sayo th« American Shipbuilder, an explanation is given of some of the curious phenomena pertaining to fog horns. It bas been found that, with acoustic signals or eirens, they are surrounded by a neutral zone, ia which the sound is not heard at the sea level. This zone is more or Ices distant, according to the height of the siren on the coast, and it has a main width of about 8400 ft. On the nearer side of this zone the sound is heard perfectly, but when it is traversed the sound weakens gradually until it becomes almost imperceptible, when it increases again, and, on the zone being finally left behind, the scund resumes its full intensity. Experiments have been made with a vessel by causing it to approach and recede from a lightship in various directions in a straight line. In each course the sound was deadened almoßt completely in a zone whoso central line was about 15,000 ft from the sires.

• . • Under Professor Frank H. Snow, of the University of Kansas, another series of investigations is toeing undertaken in the interests of the agriculturist;. Id this particular case the experiments are rather daring. They are not to cure disease, but to spread it. The particular department of Professor Snow is knowp, in the cant phrase of the West-, as the " hospital for insects." Insects damaging to crops are artificially inoculated with disease and then shipped to farmers to scatter over their fields, thns spreading a plague whiqh it is hoped will dispose of the pest. Last season consignments of disease-inocu-lated insects were forwarded to 3000 farmers in Kansas alone.

• . • Another curious development of the X-ray marvel has been found in the fact that, by using a screen coated with a certain fluorescent compound, the shadow pictures need not be submitted to the action of a photographic plate, but can be seen by the eye direct. Professor Salvioni, pf Perugia, was the first to point this out, and experiments in London have corroborated his observations. By nsing a screen covered with potassic-platino-cyanide, Mr Herbert Jackson has shown that the bones of the hand, foot, elbow, &c., can nob only be SBen, but can actually be Been in movement. The jwaibfldiuaadoofcii is to filacfl tha Ahisct to

be viewed botvreen the radiant matter tubs and the fluoreecent screen in a dark; room ; the shadow then beoomss evident on tho screen as a shadow might be projected upon a surface covered with luminous paint, Ia this way Mr Jackaon has already viewed the spinal bones in a living human body, and he looks forward at an early date to viewing la the same manner the entire' skeleton.