ANY reader of detective stories knows to watch for subtle anomalies. A dozen years ago I spotted one while investigating the history of fibre optics. In an interview in 1921, less than a year before his death, Alexander Graham Bell had said that he considered his greatest invention to be the , an obscure device that modulated the intensity of reflected sunlight to transmit voices through the open air. The choice struck me as odd, but I didn’t investigate it further.
spotted another anomaly when studying Bell’s notebook from the time of his 1876 telephone experiments.
