The Tide Table Keeper: Tides, Trade, and the Medieval English Monk Who Predicted the Sea

Before GPS. Before satellites. Before anyone thought to ask.

Every morning, the Severn rose and swallowed the world. Every evening, it gave it back. And for centuries, no one in England could tell you exactly when.

It is 1200 CE. Bristol is a city built on water it cannot fully read. Ships wait at the mouth of the Avon, crews idle, cargo sweating in the hold, merchants pacing the quayside, all of them dependent on a small brotherhood of pilots who guard their knowledge of the tides the way a ...