"After a dozen strokes," says our authority, Mr. Albert Ernest Jenks, "the sides of the groove and the edge of the piece are burned down; presently a smell of smoke is plain and before three dozen strokes have been made, smoke may be seen. Usually before a hundred strokes a larger volume of smoke tells us that the dry dust constantly falling on the pile has grown more and more charred until finally a tiny spark falls, carrying combustion to the already heated dust cone."

The fire-board is then carefully lifted and if the pinch of dust is smouldering it may now be gently fanned with the hand until the tinder catches; then it may be blown into a flame.