These singular beings dwelt in the caves of ocean, and came up to disport themselves on the shores of the islands. A favourite haunt of theirs was the Ve Skerries, about seven miles north-west of Papa-Stour. They usually rose through the water in the shape of seals, and when they reached the beach they slipped off their skins and appeared like ordinary mortals, the females being of exceeding beauty. If the skins could be snatched away on these occasions, their owners were powerless to escape into the sea again. Sometimes these creatures were entangled in the nets of fishermen or were caught by hooks. If they were shot when in seal form, a tempest arose as soon as their blood was mingled with the water of the sea. A family living within recent times was believed to be descended from a human father and a mermaid mother, the man having captured his bride by stealing her seal's skin. After some years spent on land this sea lady recovered her skin, and at once returned to her native element. The members of the family were said to have hands bearing some resemblance to the forefeet of a seal. "Of all the old mythological existences of Scotland," remarks Hugh Miller, in his "Scenes and Legends of the North of Scotland," "there was none with whom the people of Cromarty were better acquainted than with the mermaid. Thirty years have not yet gone by since she has been seen by moonlight sitting on a stone in the sea, a little to the east of the town; and scarcely a winter passed, forty years earlier, in which she was not heard singing among the rocks or seen braiding up her long yellow tresses on the shore." The magical power ascribed to the sea is shown in an Orcadian witch charm used in the seventeenth century. The charm had to do with the churning of butter. Whoever wished to take advantage of it watched on the beach till nine waves rolled in. At the reflux of the last the charmer took three handfuls of water from the sea and carried them home in a pail. If this water was put into the churn there would be a plentiful supply of butter. Sea water was also used for curative purposes, the patient being dipped after sunset. This charm was thought to savour strongly of the black art. Allusion has been made above to the rising of a storm in connection with the wounding of a sea-trow in Shetland. According to an Orcadian superstition, the sea began to swell whenever anyone with a piece of iron about him stept upon a certain rock at the Noup Head of Westray. Not till the offending metal was thrown into the water did the sea become calm again. Wallace, a minister at Kirkwall towards the end of the seventeenth century, mentions this belief in his "Description of the Isles of Orkney," and says that he offered a man a shilling to try the experiment, but the offer was refused. It does not seem to have occurred to him to make the experiment himself.