The Lighthouse Stevensons - Bella Bathurst [7]
Even when captains were confident they were clear of the cross-currents near the isles, there were reefs and rocks – Sule Skerry off Cape Wrath, the Torran Rocks off the coast of Iona and Skerryvore beyond Tiree. The entrance to the Forth is guarded by three separate obstacles – the Isle of May, the Bass Rock and Inchkeith – all of which stick directly in the path of shipping on its way to the port of Leith. A little farther northeast, there is the infamous Bell Rock, submerged at high tide and a confusion of serrated rocks at low tide. Round on the west coast, the entrance to the Clyde is calmer but prone to shallows and awkward weather patterns thrown off by the surrounding islands. Where the placid Gulf Stream soaks into the Atlantic, the area is notorious for races, currents and ‘standing waves’ (water flowing over submerged objects which gives the impression of immobility), while the whirlpool of Corrievreckan between Jura and Scarba is considered the most dangerous tide in Europe. Even on a clear day, crossing Corrievreckan involves careful calculation. Boats making the passage cling nervously to the shoreline only to find themselves speeding through at fifteen knots or more. In a dirty sea, the gully resembles Scylla and Charybdis, sucking boats down into the eddy or spitting them out to the shores on either side. Sailors who know the area well enough to avoid the centre frequently wreck themselves on the nearby coasts trying to escape.
Until the mid-nineteenth century, navigation remained a ramshackle skill. Sailors within sight of the shore depended on being able to recognise the coastline. A church roof, a solitary copice or a coastal hamlet were reference points as dependable as any more thorough knowledge of the sea’s geography. In England, Elizabeth I had made altering or dismantling the most significant coastal landmarks a criminal offence. The law had little effect. After dark, without lights, landmarks were of only the most limited help. Many accounts of shipwrecks from the time note laconically that the pilot had mistaken one bay or harbour for another, and ended up paying for it. Even when the first primitive fires were lit on headlands to mark the way, they could easily be confused with stubble fires or temporary beacons. Nor was it possible to rely on written evidence. Even now, with the benefits of sonar and satellite surveying, there is no such thing as a definitive chart. Some parts of the Scottish coastline have not been surveyed for 150 years or more; others could be surveyed till the end of time and still not keep pace with the shiftiness of the sea. In the late eighteenth century, charts, maps and pilot books were drawn up by trial and painful error, and they were as often produced by merchants or traders as by any regularised state system. It was not until 1750 that Murdoch Mackenzie published a sea chart of Orkney and Lewis based on a rigid triangulation framework. Farther south, the situation remained poor for several more decades. In 1788, Murdo Downie, the Master of HM Champion at Leith, was complaining to the government that he could find ‘no chart published of the East Coast of Scotland that could in any degree be relied upon’. The old cherub-covered maps, with their foreshortened coasts and squint-eyed headlands, might look endearing now, but for several long centuries they were the only detailed information on the British coast available. When Daniel Defoe made his tour of Scotland in the 1720s, he discovered that the Forth and Clyde did not, in fact, run into one another, as his map suggested. ‘When I came more critically to survey the ground,’ he complained, ‘I found the map-makers greatly mistaken, and that they had not only given the situation and courses of the rivers wrong, but the distances also.’ Farther north, in ‘that mountainous, barren and frightful country’, the Highlands, things were even worse. ‘Our geographers seem to be almost as much at a loss in