OPTICAL MUNITIONS
AUSTRALIAN PRODUCTION BIG DEVELOPMENTS. REVOLUTIONARY MOVE MADE. Between 100 and 150 different types of optical munitions—instruments such as range-finders, dial and telescope sights, directors, predictors, stereoscopes, and prismatic compasses—are now being manufactured in Australia. A Commonwealth Department of Information bulletin, released in New Zealand by the Assistant Australian Trade Commissioner (Mr J. L. Menzies), says that these instruments are proving comparable with those formerly imported. Optical munitions are probably the “tightest” item of equipment for every fighting force in the world, and soon after the war it became evident that Australia was faced with the problem of having to manufacture her own requirements, because supply from the usual sources abroad had dwindled seriously. The problem was immense, but in the space of a few months great and heartening progress has been made — progress, indeed, which even a relatively few months ago could not have been expected by the most optimistic. An advisory panel of scientists, most of whom were, physicists, was enrolled tinder the chairmanship of Professor T. H. Laby, F.R.S., Professor of Natural Philosophy at the University of Melbourne. Some idea of the difficulties of the problem associated with the manufacture of effective optical munitions can be gauged from the fact that in the last war it took the United States three years —from 1914-1917 —to swing into actual production, notwithstanding the vastness of her resources, both scientific and material. At one stage, this backwardness of the Allies in optical munitions threatened to cost them the victory. At the beginning, then, the Australian Optical Munitions Panel faced a disheartening task. They were told of Australia’s inadequacies in resources, and that whatever sort of job they succeeded in turning out in these circumstances. would be inferior to the overseas job. Optical munitions were needed and needed in quantity and the Panel was asked to organise the production of articles which would do at least some of the work of those previously imported. A heartening measure of success was soon recorded. For instance, the production of a stereoscope by which photographs taken from the air can be viewed in third dimension represents what to the lay mind, at least, must be a triumph. Formerly, each stereoscope imported from England to Australia cost about £7O, and even if the Commonwealth was prepared to pay highly for these English instruments they were unobtainable. But Australia is now producing effective stereoscopes at a cost of £l3 each. Six weeks after the problem of streoscope production was submitted to the Panel, stereoscopes were being produced. Their efficiency may be gauged from the fact that now both England and India have asked for samples with a view to ordering the Australian instruments in quantity. Prisms are an important component of optical munitions, and are invariably made of optical glass. They are necessary for many high-class optical instruments including binoculars, range finders, directors and dial sights. But optical glass was not available in Australia, so a substitute had to be found quickly to allow the work of making optical munitions go on. The idea came of welding layers of the best quality polished quarter-inch plate glass anti of cutting the prisms from them. Provided the prism edges are correctly orientated satisfactory results can be achieved. No matter how many thicknesses there are in the plate glass weld the 'striations'—that is, layers of glass differing in refractive index from the main glass—remain straight. In thick plate glass, however. the 'striations’ may be curved.
Although this does not seem a great or spectacular achievement, it obviated the immediate need for optical glass, and allowed the work to go on. This solution of a pressing problem represented a remarkable scientific success. Another great success was scored when a sighting telescope, an instrument used on many guns for anti-tank work, was produced. The lenses of this were made of spectacle glass, stocks of which were available. The initial instruments manufactured by this industry proved comparable with the British prototype, which used firstclass optical glass and which was made by first-class operatives. Prismatic compasses offered the Panel another field for successful effort. Today, a firm at Richmond. Victoria. is making up to 100 such compasses a day. No work like this had been attempted in Australia before, and the first production processes were filled with difficulty. The Panel members were faced with the lack of “bearings”—jewels — for compasses. Germany had excluded to Australia the Swiss supply of artificial sapphires which were used in this compass and a substitute had to be evolved. The Panel succeeded with a metal i bearing which, scientifically tested, had | been proved equal to any of the im-' ported articles it sought to replace.
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Wairarapa Times-Age, 11 June 1941, Page 6
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778OPTICAL MUNITIONS Wairarapa Times-Age, 11 June 1941, Page 6
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