"There is a spring which rises in a neighboring mountain, and running among the rocks is received into a little banqueting-room, artificially formed for that purpose, from whence, after being detained a short time, it falls into the Larian Lake. The nature of this spring is extremely curious: it ebbs and flows regularly three times a day. The increase and decrease are plainly visible, and exceedingly interesting to observe. You sit down by the side of the fountain, and while you are taking a repast and drinking its water, which is exceedingly cool, you see it gradually rise and fall. If you place a ring or anything else at the bottom when it is dry, the water creeps gradually up, first gently washing, finally covering it entirely, and then, little by little, subsides again. If you wait long enough, you may see it thus alternately advance and recede three successive times." Pliny suggests four or five explanations of this phenomenon, but is probably wide of the mark in all but the fourth one:-- "Or is there rather a certain reservoir that contains these waters in the bowels of the earth, and, while it is recruiting its discharges, the stream in consequence flows more slowly and in less quantity, but, when it has collected its due measure, runs on again in its usual strength and fullness." There are several of these intermitting springs in different parts of the world, and they are perhaps all to be explained on the principle of the siphon. In the Idyls of Theocritus there are frequent allusions to springs. It was at a spring--and a mountain spring at that--that Castor and Pollux encountered the plug-ugly Amycus:-- "And spying on a mountain a wild wood of vast size, they found under a smooth cliff an ever-flowing spring, filled with pure water, and the pebbles beneath seemed like crystal or silver from the depths; and near there had grown tall pines, and poplars, and plane-trees, and cypresses with leafy tops, and fragrant flowers, pleasant work for hairy bees," etc. Or the story of Hylas, the auburn-haired boy, who went to the spring to fetch water for supper for Hercules and stanch Telamon, and was seized by the enamored nymphs and drawn in. The spring was evidently a marsh or meadow spring: it was in a "low-lying spot, and around it grew many rushes, and the pale blue swallow-wort, and green maidenhair, and blooming parsley, and couch grass stretching through the marshes." As Hercules was tramping through the bog, club in hand, and shouting "Hylas!" to the full depth of his throat, he heard a thin voice come from the water,--it was Hylas responding, and Hylas, in the shape of the little frog, has been calling from our marsh springs ever since.