The Námar, or boiling mud-caldrons of Reykjahlid, situated among a range of mountains near the Myvatn (Gnat-Lake), in one of the most solitary spots in the north of the island, on the border of enormous lava-fields and of a vast unknown wilderness, exhibit volcanic power on a still more gigantic scale. There are no less than twelve of these seething pits, all filled with a disgusting thick slimy gray or black liquid, boiling or simmering with greater or less vehemence, and emitting dense volumes of steam strongly impregnated with sulphurous gases. Some sputter furiously, scattering their contents on every side, while in others the muddy soup appears too thick to boil, and after remaining quiescent for about half a minute, rises up a few inches in the centre of the basin, emits a puff of steam, and then subsides into its former state. The diameter of the largest of all the pits can not be less than fifteen feet; and it is a sort of mud Geysir, for at intervals a column of its black liquid contents, accompanied with a violent rush of steam, is thrown up to the height of six or eight feet. Professor Sartorius von Waltershausen, one of the few travellers who have visited this remarkable spot, says that the witches in _Macbeth_ could not possibly have desired a more fitting place for the preparation of their infernal gruel than the mud-caldrons of Reykjahlid. Among the hot or boiling springs of Iceland, which in hundreds of places gush forth at the foot of the mountains, some are of a gentle and even flow, and can be used for bathing, washing, or boiling, while others of an intermittent nature are mere objects of curiosity or wonder. One of the most remarkable of the latter is the Tungo-hver, at Reykholt, in the “valley of smoke,” thus named from the columns of vapor emitted by the thermal springs which are here scattered about with a lavish hand. It consists of two fountains within a yard of each other--the larger one vomiting a column of boiling water ten feet high for the space of about four minutes, when it entirely subsides, and then the smaller one operates for about three minutes, ejecting a column of about five feet. The alternation is perfectly regular in time and force, and there are authentic accounts of its unfailing exactitude for the last hundred years. But of all the springs and fountains of Iceland there is none to equal, either in grandeur or renown, the Great Geysir, which is not merely one of the curiosities of the country, but one of the wonders of the earth, as there is nothing to compare to it in any other part of the world.