50 years ago

Of the many craters on the Earth known to have been produced by fallen meteors, a few have left no signs of the meteor which caused them, apart from the huge holes created in the Earth's crust. Large meteorite fragments have been found in or near most craters. A possible explanation of the lack of meteorite fragments in the other cases is that the meteors concerned were of contraterrene constituency (anti-matter). In this case no traces of the meteors would remain, due to the annihilation process. One of these events, from which no fragments appear to have survived, has occurred in recent years. In 1908 a meteor, apparently of great size, was seen passing over western Russia; a few minutes later it crashed in the Siberian wastes with an explosion, effects of which were felt for hundreds of miles around, and seismographs thousands of miles away registered its impact ... No expedition to the site of its landing was undertaken until 1927, when the devastation found even at 40 miles from the site was almost inconceivable; but no fragments of the meteor were located despite the several huge though shallow craters which it had caused. If this meteor consisted of anti-matter an obvious explanation is at hand for the devastation found, the lack of meteoric material, and the great size reported in eye-witness accounts of its passage.

From Nature 26 April 1958.

100 years ago

At the London Institution on April 15, Mr Valdemar Poulsen lectured on “Telephoning without Wires.” ... The progress made in wireless telephony is shown by the fact that conversation has been carried on across Denmark from Lyngby to another wireless telephone exchange at Esberg, 170 miles distant. The reproduction of the voice was clear and distinct, and easy to recognise.

From Nature 23 April 1908.