The extraordinary property of producing rain, when spilt upon a stone, is attributed to the waters of Llyn Dulyn, in Snowdon, according to the following account, which is translated from the Greal, a Welsh Magazine, published in London, 1805.

"There is a lake in the mountains of Snowdon, called Dulyn, in a rugged valley, encircled by high steep rocks. This lake is extremely black, and its fish are deformed and unsightly, having large heads and small bodies. No wild swans are ever seen alighting upon it (such as are on all the other lakes in Snowdon), nor ducks, nor any bird whatever. And there is a causeway of stones leading into this lake; and if any one goes along this causeway, even when it is hot sunshine, and throws water so as to wet the furthest stone, which is called the Red Altar [yr Allawr Goch], it is a chance if it do not rain before night.
Witness, T. Prys, of Plas Iolyn, and Sion Davydd, of Rhiwlas, in Llan Silin."

This black lake is supposed to be an extinct and fathomless volcano, and shepherds in the surrounding mountains used to say that the appearance of a dove near those black and fateful waters foretokened the descent of a beautiful but wicked woman's soul to torment in the underworld.

In the seventeenth century people believed that if anybody had the courage on one of the "three-spirit nights" to watch beside Llyn Dulyn he would see who were to die within the next twelve months. Fiends would arise from the lake and drag those who had led evil lives into the black waters. Those who had led good lives would be guided past the causeway leading to the lake, and vanish in spirit forms robed in white. A reputed witch disappeared from the district, and a shepherd said he saw her being dragged into the black waters. [A.B.]