Gigantic explosion to study the upper layers of the atmosphere

Next Thursday, May 15th, around 7.30 pm it will be blown up to 63 km. west of Clermont-Ferrand 10,000 kg. of explosives for scientific purposes. The very exact observation of the times of arrival at large distances will make it possible to draw conclusions about the nature of the upper layers of the atmosphere. It is probable that the sound, or at least a vibration of the air, reaches as far as Switzerland; consequently, people who are interested in it are asked to make observations (from a high point or inside a house). The very exact determination of the time being of capital importance, it is necessary to act with a well-adjusted clock, the correction of which will be verified before and after the observation. Please note the exact time, the intensity, the nature and direction of the sound, that of the wind and of the different cloud species, the exact location, and send your observations to the meteorological office in Zurich. A second test will take place on Friday 23 May, around 8pm, and a third on Sunday 25 May, around 9am (Central European Time). The sound is expected to take around 15 minutes to reach Geneva, 20 minutes to Bern and Sierre and 25 minutes to Lugano, if conditions are normal.