From Colum Clarke
The telephone line repair supervisor in my local area tells me he keeps a record of lightning strikes on a map and has noticed that they are much more frequent around quarries, especially those which use explosives to break out the rock (7 May, p 30). A mile downhill from my nearest quarry, the house jumps with the blasts. No doubt the surrounding granite has developed cracks and I wonder if perhaps escaping radon gas helps ionise the air?
Bray, County Wicklow, Ireland
