Page:Popular Science Monthly Volume 30.djvu/591

Rh sulphur-springs, and the most famous of them all are those at Luchon, the hottest of which has a temperature of 154°, and requires cooling before it can be used. The seventh and last group consists of the earthy and calcareous waters, which are marked by a preponderance of the earthy salts of lime and magnesia. In baths, their action is much like that of the simple thermal waters. At Contrexéville, they are administered internally for dyspepsia, and in calculous and vesical complaints; but the precise mode of their action is not well understood. Probably much of their efficacy is due to the large quantity of an active solvent, such as hot water, which the patient is induced to consume; and this, Dr. Yeo hints more than once, may be a chief element in the virtue of all the springs.

Land-Waves.—Professor "W. Mattieu Williams maintains that the tidal waves, rushes of the sea, and other phenomena of the kind observable in connection with earthquakes, are not affections of the sea, but of the land. It is the land that undergoes the upheaval and depression that are remarked, but which, as observed by land-dwellers and made known to them by changes in the relative level of land and sea, are attributed to the latter. The great Krakatoa wave "swept half-way round the earth without being felt by any vessel out at sea. It was felt badly enough on land, and on land only. The great wave that made such havoc at the earthquake of Lisbon was evidently a land-wave. It was the rising and falling of the land, not of the sea, that buried the solid marble quay of Lisbon. As Lyell says, 'The quay sank down with all the people on it, and not one of the dead bodies ever floated to the surface.' In its place the water is now one hundred fathoms deep." An account is given in "Nature" of June 3, 1886, of a phenomenon witnessed at Stonehaven, where, at intervals, just before and after high tide, without any apparent cause, the water along the coast rose and fell from ten to eighteen inches at a time, the subsidence leaving as much as from fifteen to eighteen feet of the beach dry. The disturbance continued for three hours, during which "there was no wind, and the sea was quite smooth, but the water advanced and retired with a speed equal to the run of a large river during a soate." It was surmised that the phenomenon was due to some eruption or subsidence in the sea-bottom; but, to Professor Williams, "it appears far more probable that an undulation of the coast itself was the cause, the rising of the land causing the recession of the sea, and vice versa. A sea-wave, however caused, on advancing over a shallow, sloping bottom with a fall of from ten to eighteen inches in from fifteen to eighteen feet, would break and form a 'roller,' and distinctly show itself as a 'ground-swell.' "Many other mysterious rushings of the sea on the coast may be similarly explained. They demand more careful study than they have received.

The Rocky Mountains.—Describing the British Columbian Rocky Mountains, before the British Association, George M. Dawson remarked that the term "Rocky Mountains" is frequently applied in a loose way to the whole mountainous belt which borders the west side of the North American Continent. The mountainous belt is, however, preferably called the Cordillera region, and includes a great number of mountain systems or ranges, which on the fortieth parallel have a breadth of not less than seven hundred miles. Nearly coincident with the forty-ninth parallel, however, a change in the general character of the Cordillera region occurs. It becomes comparatively strict and narrow, and runs to the fifty-sixth parallel, or beyond, with an average width of about four hundred miles only. This portion of the western mountain-region comprises the greater part of the province of British Columbia. It consists of four main ranges, or systems of mountains, each including a number of component ranges. These mountains are, from east to west, the Rocky Mountains proper, mountains which may be classed together as the gold ranges, the system of the Coast Ranges of British Columbia (sometimes improperly named the Cascade Range), and a mountain system, the unsubmerged portions of which constitute Vancouver and the Queen Charlotte Islands. The system of the Rocky Mountains proper, between the forty-ninth and fifty-third parallels, has an average width of about sixty