MODERN SCIENCE.

New Zealand Herald, Volume LXI, Issue 18879, 29 November 1924, Page 7 (Supplement)

MODERN SCIENCE.

ITEMS OF INTEBEST.

A BEACON FOR AVIATORB.

800,000,000 CANDLE POWEK

'1 motor-track whose engine supplies electric current for lighting a powerful WSrchlight, in the form of a beacon for <nudin K aviators vrh.cn flying at night. £g recently demonstrated at McCook Field Dayton, Ohio. The same engine that furnishes motive power for the operation of the motorised veluclo also is the Eource of current for illuminating the brilliant searchlight. The light radiated by this new type b f beacon is of high intensity-300,000,000 candle power-and the reflector for rereading the rays of light measures 3g in in diameter. By the illumination radiated from this powerful searchlight, -when stationed at a landing field, the aviator when navigating the air after nightfall should be enabled to locate the landing field from a distance of 75 to 100 miles Similar beacons are employed on battleships when at sea, but, this is the fi , sfc time that such a searchlight has been adapted to purposes aHeld. **Wh en the United States Post Office Department is contemplating the innovaSn of the carriage of postal matter by Sraft at night the necessity of marking S3S fields by some form of artificial is apparent. The location £ Powerful beacons at intervals of 100 Sail- alone the route over which the SiUs are to be transported is the most Amnion suggestion as a way of. solving S??roble Sot night-flying of airplanes.

ELECTRICITY FROM DRY GAS. After the gasoline is recovered from ™£ne head gas, there remains a product EK as dry gas. Recently the Amenauthorised one of the S ?K e operating companies of the midWeVt to utilise the Sry gas for the generation of electricity, which is then used in running the well pumps. The use of drvTa* for this purpose is intended to Suce the cost of well operation as well „ hicreaso the output of the well A LIBRARY OF SAND. The Structural Materials Library at the Lewis Institute, Chicago, has mrtj CoUection a set of apecimens of sands gathered from all over the world. There J™ 2800 kinds, aU kept in bottles, and the collection is constantly being added to. . Nowhere else is there such a complete collection, and its purpose is to enable tests to be made, and values determined, in connection with cement and mortar work. m Each bottle has attached to it a label recording its source,, an analysis of the sand, the result of chemical tests, and so pn. j. TJSE TOR OLD RUBBER. Old rubber, worn-out inner tubes and the like, may be used in a composition, employed as a belt dressing and pulley cover. The rubber is first cut up into small pieces and then heated in an 'ordiSiary kettle to the desired temperature. The heat reduces the rubber to the liquid condition. Old rubber, which has been subjected to more or less oxidation due to exposure to air, is used preferably, as it produces a superior product. Old rubber which contains such substances as . zinc oxide, sulphate of barium, lampblack, etc., cives good results. A thick, heavy liquid substance is produced by the fusing process, which is no longer rubber, but which is of very heavy conBiatency, highly adhesive, of a waterproofing nature,, and capable, of adhering strongly to surfaces and of forming a frictional coating on them. BLOOD VESSELS X-RAYED. r A new field of usefulness has been opened for -the X-ray in the discovery of a method for taking pictures of arteries and veins, by two German scientists, Drs. Isidor Berberich and Samuel Hirsch, of Frankfort. The method consists, in injecting into the blood vessels a substance which is opaque to the rays, and which will permit shadowgraphs of the arteries and veins filled with it to be taken, just as shadowgraphs are now taken of bones and metal objects, and of the digestive organs when the latter have been filled with a " bismuth meal," which is also opaque ti the rays. The compound used for A-ray photographs of blood vessels is strontium bromide, which can be injected into the blood stream without harm. It is curious to noto that strontium bromide has been used in medicine for many years without anyone discovering its value in X : ray work. OIL FROM TEE NGAIO. An investigation of the properties _of the essential oil of the New Zealand native tree, myoporum lactum, commonly known ss the ngaio/ is being made by Mr. F. H. McDowall, M.Sc.j A.I.C, a New Zealander, who is now in London. Mr. McDowall, who is a science graduate of the New Zealand University, resigned the John Edmond Fellowship in Chemistry, and left New Zealand with the object of gaining further research experience in the laboratories of University College, London. There he will work in the Ralph Foster laboratories, which are reputed to be among the finest in the world, under Professor Callie. His past work on the subject of the ngaio at Otago University has shown that the main constituent of the oil is of great chemical interest and of a type hitherto undescribed. Mr. McDowall hopes during the course of his work to gain some knowledge of the real chemical structure of this compound. PRESERVATION OF FISH NETS. According to the United States Bureau of Fisheries the efficacious methods of 'preserving fish nets are tanning, tarring, and creosoting. In the tanning method the nets are left soft and pliable. After the nets have been dipped into the tan liquor it. is well to give them a treatment wiih bichromate of potash, which increases the preservative powers of the tanning materials, such as quercitron, catachu, gambier, etc. Hemp threads are afforded protection in this way as well as cotton threads but not to so high a degree. Tarring the nets is the principal method used in the United States. It <~onsists simply of passing the nets through hot tar; removing the excess tar and then partially drying. This is a very effective method as the coal tar used is an antidote against, putrefaction. Creosote oil is also used for preserving nets. It is a good preservative and causes little shrinkage. The principal objection fo its use is that it out too readily, or evaporates from the net. THE SMALLEST POWER UNIT. When one is listening to a broadcasting station, one is at the receiving end of one of the smallest power units of which man has made any practical use. The controlled currents which do work in the lond-sneaker or telephone come from the "B" bnHery and thence to the receiving tuho. The incoming impulses from the antenna or loop, changing with the change of voice currents or code currents, control the larger oulnnt of the tube through the grid circuit. The minute quantity of energy utilised by each receiver to direct and control the local battery circuit has been made significant by Dr.L. R. Whitby, director of the research laboratory of the General Electric Company in the statement that; "If the amount of work done by a house-fly in crawling up a window pane for one inch were to he put in a receiving tube—as energy coming from space—it would suffice to actuate the outfit continuously for a quarter of a century." This is the amount of energy »hich, when amplified, enables one to hear through loud-speaker or telephone I*.. iaadset.