Bragg to [J.H.Burn-Murdock], 23 Sept. 1936: has made note of his suggestion about...

Bragg to [J.H.Burn-Murdock], 23 Sept. 1936: has made note of his suggestion about plates. The common explanation of the long roll of thunder is that it is due to reflection and refraction by the masses of air of different temperatures in the clouds. The origin of the sound from different parts of the track must prolong it. Thinks the length of track is the main factor. Comments on his sound ranging experience. If observers are totally enclosed by a conductor, no electrical disturbance outside has any effect on them; comments on this. Believes the explosive force of lightening is due to the sudden vaporizion of water. Difficult to get any electrostatic effects with a Voltaic pile; comments on this.