Plural of cannel; a type of bituminous coal that is compact and burns with a bright flame.
From 'cannel coal,' possibly derived from 'candle coal' because it burns so brightly it was used like a candle. The 'cannel' spelling is a shortened form used since at least the 18th century.
Cannel coal is so bright-burning that miners called it 'candle coal'—it's one of the few coals you could theoretically read by without additional light!
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