SCIENCE and INVENTIONS.

New Zealand Herald, Volume LIX, Issue 18215, 7 October 1922, Page 8 (Supplement)

SCIENCE and INVENTIONS.

COUNTRY FIRE-FIGHTER. The risk of disastrous country fires will be considerably lessened by the invention of a moto.T-!iro |engii;e, which win be hauled by one man or trailed behind any motor-car. A Maidstone, England, firm ha-s recently put such a tire-fighting "pocket Hercules" on tho market. It is capable of throwing a jet 100 feet high with a 160 gallons-to-the-minute pressure. Tho " bantam " can- be carried tn a luggage van, and—*not the least important of its advantages for rural areas—can be taken over any kind of ground. PLASTIC WOOD. Plastic wood is the name given to a new material manufactured by a British concern, namely, a collodion preparation made with very line wood meal, and as supplied readv for use of the consistency of soft putty." This material will probably be of most interest in connection with patternmaking and moulding, for it co,n bo used for ordinary tilling and stoppng work in wood patterns" and for fillets. It adheres firmly to wood and can bo applied and smoothed down by tha thumb or a tool. It is claimed to "be water-proof, to set quite hard and can be c.ut with an otdinary tool like wood and turned in the lathe. It can also bo finished with sandpaper. It shrinks slightly in drying, but tho hardened material is not brittle and nails can be driven firmly into it without cracking it. A solvent is also, it is stated, available i.o soften tho material. EASY STARTING OIL ENGINE. Risjht through the history of the oil engine the difficulty of starting, especially when the engine is cold, has occupied the attention of inventors. Hitherto the most popular way of getting over the difficulty has been to uso high grade, oil of til© petrol tvpe for starting .and, after tho engine has got coing, to change over to tho heaw oil which forms tho cheapest fuel for such prime movers. This arrangement, however, is; reallv only a make-shift, and engineers have felt that tho problem would not be really solved until an engine was designed to "start " from cold " on crude oil. This problem has now been solved by a British firm. The engine, after receiving tho usual first impulse from compressed air starts right away with a heavy fuel oil of the quality generally used in running. In point of fact, any fuel which can be pumped is suitable for this engine, which has oeen satisfactorily running om tar oil i and even on sewerage grease. This grease 1 is in the form of a thick paste anil has j to be warmed before it can be pumped. ILLUMINATED HANDBAG. The small bag which forms onq of the ordinary items in every woman's equipment when she goes out. for the evening not infrequently contains, besides the indispensable handkerchief, a powder-puff, letters, chocolates, cigarettes, matches, and last, but by no means least in importance, a latchkey. Any one. of these articles maybe wanted in tho dark, when it is not always easily found. A/ bag with a tiny electric tamp inside, which lights up automatically when the bag is opened, removes this source of worry. The lamp is fixed to tho lining of (ho bug, and is fed by a small battery of the. torch-refill type, which is tucked away in a special pocket. In addition to discharging its ordinary fur ctions, tho catch of the bag also d<"ts the work of an electric switch. Tho bag 's opened by pressing a knob, and if the p:(ssure is then removed from' the knob, the catch springs up and makes contact, thereby switching tho current through the lamp. In tho day-time, however, or whe& no light is wanted, the knob can be kept pressed down while the bag is open, thus avoiding a wasting of current. WORK FOR LOW-GRADE ORES.

The work of the bureau of Mines of the United States on iron ores is directed chiefly towards devising means for utilising extensive deposits of low-grade ores that ! cannot bo smelted profitably by present methods. In order to utilise such ores, it is necessary that enough of tho gangue and impurities bo removed to raise the ore to smelting grade, or methods of smelting ore of lower iron content must be devised. The Itforth Central mining experiment station of the Bureau of Mines, at Minneapolis, Minn., lias continued to co-operato with the State mining experiment station in an investigation of tho reserves of low-grade ore in tho Lake Superior district, and in milling tests of samples collected in the course of the field work. This work has also included experimental tests of low-grade iron ores in the southern districts. With tho establishment, of the mining experiment station at Birmingham, Ala., more extensive work has been made possible, and a comprehensive survey of the iron and steel industry of the Birmingham district has begun. The main object sought is to develop means of beneficiating the low-grade hignly silicious ores that occur in large quantities in that district. At Minneapolis the work has been more closely related to utilising low-grade manganiferous ores of the Lake Superior district, particularly as regards the study of blast-furnace practice.

ELECTRICITY BY WIND-POWER. Some few months ago a description was, published in England of a dynamo which was driven by a windimpeller mounted directly upon the armature spindle, thus dispensing with the usual gearing for multiplying the speed of a big, slow-turning windmill. An important improvement'has, however, since been made in this device. This consists in mounting the field magnets on a spindle, and fittincr them with a sccond wind-im-. poller, which rotates in the opposite direction to the armature. This gives tho same effect as rotating the armature alone at a higher speed, and produces roughly twice the amount of -t'ectricity. The impeller for the armatw f is at one end of the machine, and tlwt for tho field magnates nt the other, A. minor modification is tho mounting of three machines on the ends of three tubular steel bars radiating from a common centre, where they are welded to a steel upright. This upright is continued downwards into a swivelling head, which is fitted with contact rings and brushes to transmit the current to the stationary support without having to use looso cables, wh>'' might eventually twist up. At the bat. of the three-bar frame is a which keeps the machines always pointinc into the wind. The dynamos go pn working day and night without and cittention when there is any wind. All bearings are of the ball type, which require oiling at long intervals. WIRELESS «« STRAYS." Wireless amateurs may often he puzzled ;by the " strays," the strange noises like i wet squibs and frying bacon which they j have probably heard in their telephohes. In the ether there are a number of stray ; waves, set up by natural causes, such as • lightning discharges. These affect nil J aerials within their rango much in the same way as genuine signals and therefore affect the telephone receivers. In the earlier days of wireless these stray signals had not been, studied much and were i termed' Xs. Nowadays thev are called "atmospherics," "statics," ''strays," or " sturbs " (American). Atmospherics may be due to naturally caused oscillations resulting from lightning, by earth-currents, or by the effect on the aerial of electrically charged particles in the air. Tkey are as a rule, worse at night. An English authority considers that the majority of strays received in Britain have their origin in the West. African regions. Unless the magnification of his set is large, the amateur will not experience much annoyance from "strays," especially if he is receiving strong signals or telephony. Another curious phenomenon, not altogether an unpleasant one, is the increase in the range i of transmitting stations during the hour j of darkness. The cause of this is the ! greater conductivity of the atmosphere during daylight t.luin during darkness. Conductors rob the wireless waves of their electromagnetic energy, hence when the atmosphere is less conductive more energy makes its way to the receiving aerial. ' Occasionally a wireless station may hear I signals trom another so far distant as to make it impossible to explain tho matter away by regarding it as a "night effect.-