“I do not know, it always does it and does it thoroughly.” I venture the following explanation. Recalling that the accepted idea of the interior of a geyser is that of a large chamber of heated rock nearly filled with water and that below the water line there is a tube which bends down then upward into a chamber in the rock. The water becomes superheated. The steam and other gases in the dome of the chamber are under terrific pressure on account of the great heat and the weight of the column of water above, (if one thinks of the geyser tube connecting the underground basin with the surface as the letter J). When the pressure in the dome over the water becomes greater than the downward force of the water in the long arm of the tube then there is an upward movement through the tube. The expanding steam throws out some of the water. This reduces the pressure on the superheated water in the basin and some of the water bursts into steam to continue the action. This process goes on till basin, tube, underground chamber and connecting tubes are empty. Distant and cooler underground waters now rush in freely to refill the system and time produces a repetition. It is easy to construct glass apparatus in the laboratory to demonstrate this phenomenon. But what of the soap? This substance is composed of materials which quickly break down into hydrocarbon gases and increase the pressure in the chamber, just like oil spurted into the superheater of a water gas machine. Many of the boiling springs, spurting jets and fumaroles are alike in this locality but three of them deserve special notice. _Blesi_, Blaze, as the white stripe in a horse’s face, is a charming grotto. It is a double basin connected with a tunnel just beneath a narrow bridge near the surface. These basins are about thirty feet deep. One is eighteen by twelve and the other thirty by twenty feet in the longest and shortest diameters respectively. The water is wonderfully transparent and the white silicious lining of the grottoes reflects from the sky the delicate shade of blue transforming it into a huge cavity of lapis lazuli. _Blesi_ is the traveler’s friend. It provides hot water for the bath, cooks his food, warms his couch through the medium of the hot water bag and prepares his coffee. Many a leg of mutton, many a brace of birds and innumerable are the eggs that have been faithfully prepared with its friendly heat. It is an easy method of cooking. Fill a pail with eggs and submerge it till they are soft, medium or hard, the time required is the same as in the kitchen. Place the meat in a cloth bag and do the same. Dip up the water and pour it upon the freshly ground berries, lo! the coffee is prepared and your meal is ready. This spring never erupts but pours out a steady stream which flows down the slope to join the runway from _Geysir_.