Since the first world war, British scientists had been experimenting with acoustic locators in one form or another. Early tests were made with scaled-up ear trumpets. Other fanciful proposals involved digging large arrays of pits where sentries would sit and listen for intruders. The plan was that, when an aircraft was heard, the\u00a0operator would\u00a0communicate\u00a0the exact time of the event a central headquarters\u00a0where by comparing reports from other pits, the track and speed of the aircraft could be calculated. Needless to say, further work was required to make\u00a0a workable system.<\/p>\n By 1930 the current state of the art was the \u2019strip mirror\u2019. A prototype sound locator of this design was built at Denge in the UK, followed a couple of years later by the Maltese mirror. There were plans to construct similar mirrors at strategic sites throughout the empire including five covering all approaches to Malta. As it turned out, the Maghtab mirror was the only of these concrete curiosities built in Malta. It is also the only one outside the UK. The invention of radar quickly rendered sound locators obsolete.<\/p>\n Il Widna is 200 feet from end to end and rises to a height of some 27 feet. In front of the wall is a sloping expanse of concrete and the \u2018listening trench\u2019 where 20 very sensitive microphones\u00a0would have been\u00a0located.\u00a0\u00a0The microphones were monitored,\u00a0and their output was interpreted by operators in a small room at the back of the mirror. When the mirror was commissioned in\u00a0December 1935 \u00a0it had already proved to be effective in detecting incoming aircraft at a range of up to 36 miles. In other trials,\u00a020 \u2013 25 miles was more typical but planes were slower in those days and even from this shorter distance, would have taken a good 10 to 15 minutes to reach Malta\u2019s coast.<\/p>\n When I visited the mirror I found that you could get a perfectly good view of it across the fields from the public road. It is still painted in a camouflage scheme designed to make it difficult to spot from the air but from the ground it is very easy to see. Just look for GO Malta\u2019s satellite dishes.<\/p>\n \n In the National War Museum in Valletta, there used to be a small model of\u00a0a sound locator or \u2018acoustic mirror\u2019. Constructed in the days before radar was invented, such mirrors were designed to reflect and focus the sounds of approaching aircraft so that their bearing could be calculated and an appropriate welcome organised. The Malta … Continue reading Il Widna. The biggest ear in Malta<\/span> ![\"Il](\"http:\/\/farm4.staticflickr.com\/3339\/3487183576_c44d06b679_z.jpg\" "\\"Il")
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