Do you ‘damp down’ or ‘tamp down’?
‘Dampfschifffahrt!’ shouted my husband as though it were funny. I had been saying how strange it was that explosive gas in a coal mine should be called firedamp, since damp things burn with difficulty. Nevertheless, my husband was on to something, for the German Dampf, steam, is related to English damp. Damp in English originally meant ‘a noxious exhalation’. Caxton used it in the 15th century when writing of a prophecy of Merlin about a goat breathing from its nostrils a ‘damp’ that would betoken hunger. By the 17th century various kinds of damp were feared in mines, fulminating damp or firedamp, which caught fire from the miners’ candles, and
