Tide mills are among the more ingenious solutions to the problem of power in a pre-industrial landscape. Rather than relying on a river's steady flow, they capture seawater in a millpond as the tide rises, then release it in a controlled rush through a wheel as the tide falls. The result is a mill that works to the rhythm of the sea rather than the seasons, which made such structures both practical and oddly precarious, dependent entirely on coastal geography and tidal range.