Page:Popular Science Monthly Volume 25.djvu/510

496 left out, and yet the comparatively unimportant geyser area of the Azores can perhaps be considered the African representative, while in the boiling lake of Dominica, and the water-volcano of Guatemala, Central and South America may be said to have geysers on a grand scale.

The difference between geysers and ordinary hot springs is not readily explained, nor always recognized, although the difference between a quiet hot spring and a geyser in active eruption is very marked. However, these are the extremes, and between the two there is every grade of action. Some geysers at times appear as quiet springs, and others are constantly in active ebullition. A geyser may be defined to be a periodically eruptive or intermittent hot spring, from which the water is projected into the air in a fountain-like column. The word hot in this definition is italicized because springs containing a large amount of gas may simulate geysers, as in the case of the Kane geyser-well in Pennsylvania, which spouts regularly, and the artesian well at Rank Herkany, in Hungary, which is fourteen hundred and fifty-seven feet deep, and spouts at regular intervals to the height of one hundred feet. Nordenskiöld discovered an intermittent cold geyser-like spring spouting through the ice-field of Greenland about thirty miles from the coast. Almost all the constantly boiling springs have periods of increased activity, and those which spout only a few feet into the air have been classed as pseudo geysers. There are several localities of the latter in the United States, particularly in California, and Nevada. The geysers of California belong to this class, as do also the mud-volcanoes of Southern California, although some of the latter throw columns of water to the height of twenty feet, and are true geysers. Besides the Yellowstone National Park, the Haukadal area in Iceland, and the Taupo region of New Zealand, which are the geyser regions par excellence of the world, there are a number of places where a few individual geysers are known, besides the Thibet area and that of the Azores. In Mexico, at Aguas Calientes, near San Luis Potosi, there is a geyser which spouts to the height of ten or twelve feet. The Volcan de Agua, or water-volcano, of Guatemala, and the boiling lake of Dominica have already been referred to. The latter has been known since 1777. It is a seething caldron of unknown depth, measuring two hundred by more than one hundred yards, situated in the Grand Soufrière of Dominica, at an elevation of twenty-four hundred feet above sea-level. It is sometimes quiet, with a temperature of 96° Fahr., and at others is in active ebullition, with a temperature above the boiling-point, the water being thrown in jets into the air with a noise like the discharge of artillery. At Atami, in Japan, there are intermittent springs which spout about six times daily, although not with any exact regularity. An immense volume of steam and slightly sulphureted water is ejected. Geysers are found in Batachian, one of the Moluccas, and at Nolok on Celebes there is a bowl-shaped spring