Page:A Book of Dartmoor.djvu/45

Rh Here among the clitters, where they form caves, a search may be made for the beautiful moss Schistostega osmundacea. It has a metallic lustre like green gold, and on entering a dark place under rocks, the ground seems to be blazing with gold. In Germany the Fichtel Gebirge are of granite, and the Luchsen Berg is so called because there in the hollow under the rocks grew abundance of the moss glittering like the eyes of a lynx. The authorities of Alexanderbad have had to rail in the grottoes to prevent the gold moss from being carried off by the curious. Murray says of these retreats of the luminous moss:—

"The wonder of the place is the beautiful phosphorescence which is seen in the crannies of the rocks, and which appears and disappears according to the position of the spectator. This it is which has given rise to the fairy tales of gold and gems with which the gnomes and cobolds tantalise the poor peasants. The light resembles that of glow-worms; or, if compared to a precious stone, it is something between a chrysolite and a cat's-eye, but shining with a more metallic lustre. On picking up some of it, and bringing it to the light, nothing is found but dirt."

Professor Lloyd found that the luminous appearance was due to the presence of small crystals in the structure which reflect the light. Coleridge says:—