SCIENCE NOTES.

Otago Witness, Issue 2456, 10 April 1901, Page 62

SCIENCE NOTES.

— "Riddles in Iron and Steel" is the subject of an interesting paper by Paul Krutzpointner. in Caller's Magazine for February. Many of these riddles are at present unsolved, but it is to the interest of manufacturers and metallurgists to attack them. W.hy is it that we can laise the strength of soft staybolt iron of, say 47,0001b per square inch to 60,0001b per square inch either by heat treatment, or by repeated application of stress? Why is steel coming from the rolls or hammer weaker, and less ductile, than the same steel is after left lying a day or two, or, better still, a week? There is no doubt that many tons of suitable material. ha-"c teen either thrown out by the mill people themselves or were rejected by the inspectors because it failed to meet specifications, pausing needless vexation and friction simply because neither the one nor tho other of the parties knew that steel i=s in a disturbed physical state after rolling or hammering, no matter how good the mat" ; al, and sho\ild bereft to rest, the longer the better. Now, ■what takes place in the steel during the period of rest? Another riddle is that we can raise the elastic limit and ultimate strength by a successive application of stresses very much above the original strength. What law. if it is law, governs the phenomena? Personally, the author is convinced that many errors of design or inherent weakness of the steel have been modified in their probable consequences, and breakdowns averted, by this peculiar property of steel to gain in strength, if allowed to rest after ha\ing been subject to stress within certain limits. The lesson the writer draws from these end other riddles in iron and steel is thi. methods of testing Bhould be nade uniform — annulling, ten.pning, measuring, and in crscneunc; the (jhemical composition ci the metal. At pie-

sent, we know comparatively little about steel. —Of recent years nearly every town is provided with an electric generating plant. and frequently the wires are strung alont» : country roads from town to town. This fact has led a man named M'Nair to attempt the iT3a of electricity on the farm. He has devised a curious pen some 15ft square, i built of wire and mounted on broad, flat I wheels. - This pen is designed to run in ' any pasture, though it be hilly. Wires : connect it with a small motor stationed at i one side of the pasture, this in turn being connected with the electric wires from which power is derived. A turn of the button and the pen slowly creeps across the field. That is the essence of the invention, and simple enough it seem?. A machine of this type is being experimented with at the Agricultural Experiment Station of Michigan, at Lansing. Two lambs and part cf I the time an eld ewe ha\e been pastured !in the pen during the summer. The field js planted with lucerne, growing thick and heavy. The pen is so arranged that it crawls the full length of the pasture in one month, travelling about two feet an hour ; at the end of this time it is switched around and travels back again. As it moves, the sheep cat every bit of the- fodder, eagerly cropping next the forward side of the pen as it runs over new ground. A bit of canvas duck is hung over the corner of the pen co that the sheep may be well sheltered, and, curious as it may scorn, they have become so accustomed to the moving of the pen that when they l.c down to sleep they snuggle up close to the forward end of the pen, so that they may lie as long as possible without being disturbed by the rear end of the pen as it creeps toward them. When the pen has passed, of course, the lucerne that has been cropped by the sheep immediately grows up again, and by the time the pen has made its monthtly circuit the pasture is again in good condition. The advantages of this electrical pen lie in the fact that the sheep are kept from running over, half-eating, and trampling down a large amount of pasture, and it 1-eeps the sheep quiet, so that they lay on fleah rapidly. — Electricity. — Professor Eliver Oatis (says the Liverpool Post) has been giving a few predictions a=j to the future of electricity to an American newspaper. Here ara a few of them: Mcaii3 of electrical communication will be developed to an extent now incredible. Wireless telegraphy, telephony, and telephoty, for all distances over and through the earth, will be accomplishnd, fo that we may sp°p!c to persons in distant countries, and p( o them while we are talking to them; ciiA this art will be perfected so that an entertainment gi\en in London will be heard and witnessed in San Francisco in natural colours, natural size, etc. In like manner mechanical power will be transmitted thremgh the ether to short distances without wires to many different machines in the same or adjacent buildings. Electric printing will displooe all present forms of printing, and it will print in colours. The printing will be done without ink or without inked ribbons upon electro-chemically prepared paper. With electric pens we will write on chemically preparad paper without ink or leade. The errnrgy of fuels, continues tho professor, iv ill be directly converted into electrii city without intermediate transformations of energy through batteries and dynamos. Practical results will be obtained in the utilisation of the power of natural electric waves, in the circumambient, intermolecular ether. Just as we now use natural waterfalls in producing power, so we will utilise natural electric waves of the ether to turn our wheels. Electricity will be an important factor in the accomplishment of aerial navigation, the practical solution of which will be accomplished early in the next century. It will profoundly modify industrial and social conditions; it will turn the -whole world into a neiglibouihood ; it will profoundly alter many forms of industry. Electricity, magnen-m, and cataphorens will ba applied to the separation of all kinds of powdered or particled substances from c?ch oilier, as bran from flour, gluten from ; stnic I ], particled impurities from powdered fubotanccs; gold, copper, and iron from s-amK giavel-, ninl crushed locks; in fact, anything that is 111 part:clob whatsoever can be elccUie-jiiy separated from auvthime el^e.

— "Irip," in the LcccU Mercury, writes as follows en Wprn^rke's actinoi' cter and sensitometer : — One of the most useful inventions emanating f1 om the piol'fic brain of the late Loon Warnerke was his a^tinorncter, used for testing tbe intensity of light. Briefly, the principle consists of exposing a di?c of phosphorr scent material (calcium suluhide) to light, v, hen the la&t number \islble by this phosphorescent light on circles of gradually increased opacity. Mewed through a fmall telescope in the lid of the instrument, is taken as indicating the intensity of the light. Warnerk-e's sensitometer consists of a glass plate, having Woodburytype impressions, forming 25 squares of steadily increasing opacity. The source of light is a phosphorescent tablet, made with calcium sulphide. To u*e the instrument a sensitive plate is placed in contact with the sensitometer in a special frame supplied with the apparatus. The phosphorescent tablet, excited by burning one inch of magnesium ribbon clo°e to it, is allowed to re=t a n n inute in order that its luminosity may become constant. The plate is then exposec' to this light through the sensitometcr scieen rfor 30 seconds, and developed, when the last number which can be read after fixing is taken as the Fensitometer number of that plate. With the instrument is supplied a scale by which the relative speeds of different plates can be readily found. In 1870 Warnerke commenced experiments in the use of paper as a support for the sensitive film, in place of glass, for which he also invented a special 1 oiler dark-slide. He was also one of the pioneers of panoi?.mir- photography upon continuous bands of negative paper ; and, later, he conducted a series of investigations in collodion emulsions, which have proved of considerable value.

— Some new experiments bj r M. G. Sagnac on the transformations of Rnnlsjen rays by matter anpear in a recent Bulletin of the French Physical Society. The study of the electric action of the secondary ray 3 emitted by a body affords a tesu of the prebence of small quantities of lelatively active substances, such as copper, iron, aluminium. Hence, also, a method of searching for new elements. The energetic absorption of the more active rays from such a metal a3 platinum in the first few millimetres of adjacent air has been \erified diiectly by rarefying the air surrounding the metal. Finally, a pencil of Rontgen rays discharges a conductor even when it doe 3 not pass through the portion of air acted on by the electric field of the conductor. It is sufficient that the rays shall traverse a portion of air separated fi om the field of the conductor by a Faraday screen (~ueh as a metal gauze), and that there shall be a field of force in the part traversed, of like sense to that due to the conductor. If the charge of the conductor is reversed in sign, the rate of discharge is altered in the ratio of 1 to 10 or 20, but in the absence of the field in the second reg.on no such change takes place. SI. Sagnac's explanation of the phenomena is that the ions produced in the second region acquire, nnder thj influence of the external field, sufficient kinetic energy to carry them through the openings cf the screen into the region surrounding the conductor.

— The recent researches intensify the impression that is slowly gaining ground among the public that it is impossible to eliminate bacteria from our li\es, pven in the most unlikely situations. The air of mid-ocean a»d sterilised milk would seem to be the last places to look for organised life, and yet, according to Mmcrvini, there are more bacteria in air at sea than were found even by Fischer in his classical investigations, and De Weber finds a rich flora in the sterilised milk of commerce. It is true pathogenic forms were not found in either of these investigations, but that does not prove their absence. In a case that has been occupying the attention of the courts recently this point was strongly brought out in evidence by Dr Hewlett, of the Jenner Institute. The case in question was an action brought by the Borough of Battersea against the Lambeth and the Southwark and Vauxhall Water Companies in reference to their supply of water for domestic purposes. The allegation of the applicants was that on certain occasions water unfit for domestic consumption had been supplied. The answer of the vater company was that Professor Dewar, Sir William Crookes, and the late Sir E. Franklin had made regular analyses, which showed that the water was of good quality. The point that came out in evidence that immediately concerns us was whefher the failure to find pathogenic organisms in water was any evidence of their absence.