SCIENCE NOTES.

Digger (Invercargill RSA), Issue 11, 28 May 1920, Page 14

SCIENCE NOTES.

SEARC H i JG H T CON TROI - , It has been iound by experience- that an observer operating a military searchlight finds it difficnlt to train the fearchbght on the target whjen he is stationed close tj the searchlight itseif. Ihe reason lor this is that the observer at the lamp is handicapped by the dazzling cfiect of ihe bright beams on the eye. On accpunt of this feature of searchlight operation, rernote-control schemes have been devised whereby the observer is stationed at a distance of sorce 500 feet from the searchlight itself and there trains the lamp upon the target by ineans oi electncal control. THE 110.MK ZOO. The zoo for every mirsery, with lions which roar, canaries that sing, and ducks that really quack is the latesi outcome of gramaphonic invention. It is the invention of a yourg Englishman. Another form of the talking toy, is the story-book which tells its own stone These books ara full of pictur.es, and one can be placed on any machine. Ihe animals or birds are of cardboard, and contain, like the books, a flexible disc rccord. The performance in every caae is to a musioal accompaairaent. Little Po-Peep tells why she has lost her sheep and the mocking-bird mocks or the l.ion roars in a effectivc maata er These toys have great educational possibilities, and on the backs of the pmtures are short natural history stories. ONE-PIECE CONCRETE HOUSES. Some years ago Thomas Edison invented a method of pouring concrete into a single mould and turning out- a house. This scheme, much ridiculed at the timo, has progresbcd, Eourteen four-roomed, twostory houscs of this type have just been completed at Union, New J orscy.r and twenty-liye four-room, and fifty six-room, fcwo-stor.ey houses are being built at Phillipsburgh New Jersey. The basic idea is that of die casting. Sectional standardised, he&vily-built-up wooden forms are so made that they form a mould, as thotigh a pattern house had been moulded insido thern and thon withdrawn. They are painted with grey lead and oiled heforo use. This mould is.then filled with molten concrete, instead of the molten tnetal used in metal casiings. The forms are then rernoved and set up for the next house.

A REM.VREABLE TREE. Tltere flourishes in most paris of the Australian continent, especially in Western Australia, a species of Australian grass- tree known as the "olackboy." The pecuiiar mteresCof this trce, which grows to a norma] height of from seven to ten feet, is the variety of CQmraercial purposes it which it can be put. The tree contains gum in large quantities, and among other hy-products extracted under treatment are tars (free from harmful acids), tarjaulin dressings, rope and sanitary tars, lacquers (such as Japan black), steam and refrigerating pipe lagging, paint for ironwork that rcquires stoving at high temperatures, stains and -paints ; phenol, benzol, and alcohols, coke, potash, and pyrogeneous acid. Not only have all the articles alrcady enumerated been obtained, but a company recently formed to extract them ako intends to produce dyes, perfumes, and formalin, and various kinds of varnishes. MAKINO PHOTQPLAYS AT NIGHT. Most modern cinema studios are provided with rnercu.iy-vapour lamps on overhead racks and floor stands, so as to givo any kind -0!' illumination desired. The overhead racks are suspended from a steel-beam framework that travels along on the side raili, so as to bring ihe lamps over any part of the studio floor. While flaming arcs are stili used in some studios, the mercnry-vapour tubes to-day ara predominant- for many reasons. The lilminous element of the latter type of lamp is a luminescent arc, in a highly , evacuated tube of glass, formed between a mercury cathode and an anoxle of mercury or other metal not attacked by it. The large output of actinic radiation from mercury -vapour lamps gives them spccial advantages in the. ficlds of photography. Aithough the light from the mercury lamps is a ghastly green, which is mcst unpleasant and distorts all colour schemes, it is relatively comfortable fo? the actors, and excellent frorn the photographic point of view.