Here, where two strong streams met with terrific force, the turbulent water whirled about with wild irregular motion, and we were swept now one way, now another, until it seemed useless to fight against the current that controlled us. We were, in fact, in the midst of that dangerous vortex locally known as the Swelkie. Those who know the secrets of the ocean currents of the northern seas have their own scientific explanations to give; but our native boatmen and sailors, who were not so well acquainted with the eccentricities of the Gulf stream as with the popular legends of Orkney, accounted for the Swelkie in this way:
A certain King Frodi had a magical quern, or hand mill, called Grotti; the largest quern ever known in Denmark. Now Grotti, which ground either gold or peace for King Frodi as he willed, was stolen by a sea king named Mysing, who set the mill to grind white salt for his ships. But it happened that Mysing had only learned the spell to set the mill going, and knew not how to stop it. His ships, therefore, became so full of salt that they sank, and Grotti with them, before they could reach the islands of Orkney; hence the Swelkie. This took place to the northwest of Stroma Island, and ever since the sea there has not rested, for as the water falls through the eye of the quern, it roars and rushes about, and the quern goes on grinding and grinding salt, and giving its saltness to the whole ocean.
The mist having lifted, Captain Flett had a reef or two let out, and himself took the helm until he got us into calmer water, when we luffed to the windward and headed for South Ronaldsay, with a stiff breeze springing up that gave us a clear seaway to get past the Lother Reef, when we sailed steadily through a lesser rush of tide across a quiet, landlocked sea, into the little haven of Burwick, where in the gathering darkness the chain went rattling down, and we came to a restful anchorage.
But our stay at Burwick was not for long, as we had lost much time in the outer sea, and the skipper wanted to get round to St. Margaret's Hope. No sooner had we put a boatload of goods ashore than we set sail again. And now that we were in smoother water, I was not allowed to shirk my watch, but had to spend the better part of the night on deck.
A little after midnight we were sailing under easy sail through the dark Sound of Hoxa. I was at the helm, the mate walking the deck in front of me. The night was extremely cold, and some light flakes of snow were falling. I had difficulty in making out the points of land as we passed, but Jerry was at the bow, and I depended upon him and Peter for my steering. Just as we were abreast of Stanger Head, on the little island of Flotta, I thought I saw a small vessel creeping along, well inshore. I drew the mate's attention to it, and he was denying me, when a bright flash of light was seen, followed by a loud report, as of a small piece of ordnance. Peering through the darkness, we could distinguish the sails of a large cutter, which was now bearing down upon us.
"It's the Clasper," said Jerry, coming aft.
"Confound him!" said the mate. "Does she take us for a smuggler?"
From these words I at once understood the meaning of the shot that had been fired; the revenue cutter had evidently mistaken the Falcon for one of the famous smuggling craft of Scapa Flow.
We were at once hauled round, and a boat from the Clasper came alongside. A sprightly young lieutenant climbed over our starboard bulwarks, followed by a sailor who carried a large lantern. This the officer took from him, and coming aft to where we all three stood, he held the light aloft peering into our faces.
By this time our skipper came up from the cabin, rubbing his sleepy eyes.