Reading Old Maps of Britain's Coastal Trade Routes

Charts as Time Machines

There is a particular pleasure in unfolding a coastal chart that is two hundred years old. The paper crackles, the ink has gone the colour of weak tea, and the whole shoreline of Britain lies before you in a language that is half navigation and half poetry. Long before railways and motorways knitted the country together, almost everything moved by water: coal, corn, salt, timber, slate, fish, cattle and people. Old charts are the clearest record we have of that world, and they are far more readable than most people expect. Learn a handful of conventions and you can stand on a harbour wall and reconstruct, quite precisely, what happened in the water in front of you.

Reading the Language of the Sea

Start with the numbers. The small figures scattered across the water are soundings, depths recorded by lead and line, usually in fathoms and feet. A cluster reading 3, 2½, 2 tells you a bank is shoaling; a run of 8, 9, 10 marks a channel. Beside the numbers you will often find a word or two describing the seabed — "blue mud", "fine sand", "shells", "rock". Fishermen and mariners read those words as a kind of address: certain fish on certain grounds, good holding for an anchor on others.

Then look for the marks. On a good chart you will find:

• Leading marks — a church tower, a mill, a beacon or a pair of white-painted stones that, in line, guide a vessel through a narrow entrance.
• Perches and beacons — wooden posts standing on the mudflats, often with a basket or a cross on top, marking the edge of a channel.
• Compass roses and rhumb lines — the faint radiating lines that show the bearings used to sail a course, plus the magnetic variation noted in the corner.
• Anchorages and hards — little anchors sketched in sheltered water, and the slipways where cargo was hauled up the shore.

The handwriting matters too. The copperplate italic of a surveyor's fair copy tells you this was intended for sale; the crabbed pencil annotations, adding a new buoy or a drying sand, tell you it was used at sea.

Following the Coastal Trade: Coal, Corn and Contraband

Pick a stretch of coast and the trade routes write themselves into the map. Off Northumberland and Durham the charts are full of collier tracks, a steady procession of square-rigged brigs beating south to London with coal — the "coals from Newcastle" that heated the capital and gave us the phrase about carrying them back again. Further south, the Essex and Suffolk estuaries show oyster beds, layings and dredging grounds. The West Country charts are marked with pilchard and mackerel grounds; the Yorkshire coast with herring. Bristol Channel charts carry the constant traffic between Welsh ports, Somerset havens and the great western harbours.

And then there is the trade the charts barely mention. A blank stretch of sand, a deep-water channel hugging a lonely shore, an anchorage tucked behind a spit and out of sight of the customs house — reading a chart with smuggling in mind is an education. The preventive services knew it too, which is why the coast is dotted with watch houses, and why revenue cutters appear so often in the accounts of those same waters.

Lighthouses and Seamarks on the Chart

Lighthouses appear as small stars or dots with a flourish of light, annotated with character and range: "Fl(3) W 10s", or on older charts simply "light". But the tower is only the most dramatic of the marks. The chart records the whole system that made a coast approachable in poor weather:

• daymarks painted on cliffs, gable ends and piers;
• leading lights, often a pair, set one behind the other so a vessel holds a safe line;
• bell buoys, whistling buoys and, later, light vessels stationed off the worst shoals.

Visit a lighthouse and take a chart with you. Standing at the base of a tower on a headland, you can see at once why that particular point was chosen: the long approach, the off-lying reef, the narrow passage that needed a light on both sides. Where keepers' log books survive, they record the same geography in weather and wreck.

Planning Your Own Reading Trip

You do not need a research library to begin. County record offices, harbourmaster's offices, maritime museums and local studies collections hold charts, harbour plans and tide tables, and most are glad to lay them out for a visitor. Many national collections have digitised nineteenth-century charts, so you can study the water at home before you travel to it.

A practical method for a coastal walk:

• Choose a short stretch — five miles is plenty.
• Find the earliest chart of it you can, plus a modern walking map.
• Note the places named on the old chart that no longer exist: a lost haven, a ferry, a quay.
• Walk the route at low water, when the seabed the surveyor measured is briefly visible.
• Compare the shoreline then and now; erosion and silting tell their own story.

Tides, Wrecks and the Shape of the Shore

Two last things to read. The first is tide. Old charts often carry tide tables and notes on the set of the stream — "flood runs strong to the eastward" — and these explain where sandbanks once lay, and where they may still be creeping. The second is wreck. Look for the symbol of a mast or a hull, or the abbreviation "wks" set against a sounding. Each one is a story, and more than a few lighthouses were built because of it.

Read enough of these charts and the coast stops looking like a backdrop. It becomes what it was: a motorway, a marketplace and a workplace, marked out in fathoms and ink, with a light at the end of every hard passage.