Page:Popular Science Monthly Volume 45.djvu/444

428 An itinerary of the way was drawn up about 1154 by Abbot Nicholas, of Thurgör, in Iceland. It was a kind of guidebook for pilgrims. The climbing of mountains has occurred sporadically from ancient times. Hadrian climbed Etna to see the sunrise. In the eleventh century an attempt was made to climb the Roche Melon, but the summit was not reached till 1358. Toward the end of the thirteenth century Peter III of Aragon climbed Canigon in the Pyrenees, and saw a dragon on the top. In 1339 Petrarch climbed Mont Ventoux, near Vaucluse, "to see what the top of a hill was like." Charles VIII of France sent one of his chamberlains up the wall-sided Mont Aiguille in 1492. Leonardo da Vinci's general scientific curiosity led him to pay attention to mountains, and he appears to have ascended some part of Monte Rosa to a point above the snow line. In the sixteenth century the study of mountains advanced considerably, and a group of regular mountaineers was almost formed at Zurich, but civil and religious troubles blighted their enterprise. Conrad Gesner and Josias Simler were their leaders. The former appears to have been infected with the regular mountaineering ardor of the modern sort. Simler published a valuable and interesting book about the Alps, in which he gave sound, practical advice to climbers. During the first half of the seventeenth century mountains were neglected. Dragons were still supposed to linger among them, and they were thought to be the homes of devils, against whom outpost chapels were built.

Peat-moss Atolls.—The attention of Mr. Conway Macmillan has been directed to examples of a peculiar and hitherto unrecorded peat-moss formation observed in some of the lakes of Minnesota. From their position in the middle of ponds of considerable size, he has named them sphagnum atolls. Ballard's atoll is situated in an almost circular pond about a hundred and fifty yards across, which is surrounded, except for a short distance on the west, where a channel has been cut between two low jutting bars. The atoll appears from the surrounding hills as a ring of green, conspicuous and sharply defined, about seventy-five feet in diameter, and having a uniform width of about ten feet. Another atoll, Anderson's atoll, is in a pond about fifty yards across, with high banks, and forms a ring within a foot or two of twenty yards in diameter and having a breadth of about twelve inches. Both atolls support a diversified vegetation, which is not alike on the two. This vegetation likewise differs from that of the pond outside and of the inner lagoon, and varies with the development and desiccation of the atoll. The origin of these formations is ascribed by the author to a season of gradual recession of the waters of the pond, when a loose turf was formed, lining the edges of the pond, followed by a season of comparatively rapid increase in area and level, when this surface became detached from the shore. The atolls then probably first appeared as annular floating bogs, separated from the shoreward turf as a result of the original zonal distribution of littoral plants and the rise of the waters, together with the favorable concurrence of a group of special and necessary conditions. Some of the apparent conditions of atoll formation are a definite maximum size and depth of the present pond; considerable height and regularity of the banks of the present pond (whereby the zone of vegetation is protected from violent winds); a regular and gentle slope of the pond bottom from shore to center; a definite original character of littoral vegetation when the pond was at a low level; a reduction within minimum limits of the lateral pressure and tension of winter ice; and a comparatively prompt anchoring of the atoll upon the bottom.

Dakota Climates.—The Dakotas are divided, according to Dr. D. W. Robinson, into two climatic regions by the range of hills and highlands known as the Missouri Divide. In the east divide country "many of the essential characteristics of an ideal health region are present. . . . Excessive cloud and dampness are not present beyond what is needed for successful agriculture. The air is rare, pure, and exhilarating. Diseases of an acute character are not extensively prevalent, and outbreaks of epidemic disease are rare and easy to control." The upper Missouri basin, which is about three hundred miles long, between a hundred and three hundred miles wide, and rises from twelve