From Jim McHardy, Clydebank, West Dunbartonshire, UK
As your article states, it is very likely that will-o'-the-wisps are caused by the ignition of methane or phosphine when bubbles of these merge(11 October, p 19).
High-speed propellers and pumps are affected by cavitation when the blades are travelling so fast that bubbles of vapour appear and collapse very rapidly. This violent bubble collapse can lead to extremely high pressures, temperatures and shock waves. This would also ignite the flammable gases produced by the decomposition of the organic material in the marsh and explain the “ghosts and spirits in marshes”.
This does not, of course, imply that other apparitions are not to blame for some of the sightings, especially at Halloween!
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