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আলেকজান্ডার গ্রাহাম বেল





Baddeck, Nova Scotia containing many of Bell's experiments and models


Boston on 27 August1880, presenting the photophone, very clear description; published as "On the Production and Reproduction of Sound by Light" in the American Journal of Sciences, Third Series, vol. XX, #118, October 1880, p.305-324 and as "Selenium and the Photophone" in Nature, September 1880

