428 



THE POPULAR SCIENCE MONTHLY. 



1128. An itinerary of the way was drawn 

 up about 1154 by Abbot Nicholas, of Thur- 

 giir, 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 Pe- 

 trarch climbed Mont Ventoux, near Vau- 

 cluse, "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 gen- 

 eral scientific curiosity led him to pay atten- 

 tion to mountains, and he appears to have 

 ascended some part of Monte Rosa to a point 

 above the snow line. In the sixteenth cen- 

 tury the study of mountains advanced con- 

 siderably, and a group of regular mountain- 

 eers was almost formed at Zurich, but civil 

 and religious troubles blighted their enter- 

 prise. Conrad Gesner and Josias Simler 

 were their leaders. The former appears to 

 have been infected with the regular moun- 

 taineering 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 moun- 

 tains were neglected. Dragons were still sup- 

 posed 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 ex- 

 amples of a peculiar and hitherto unrecord- 

 ed peat-moss formation observed in some of 

 the lakes of Minnesota. From their posi- 

 tion in the middle of ponds of considerable 

 size, he has named them sphagnum atolls. 

 Ballard's atoll is situated in an almost circu- 

 lar 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 de- 

 fined, 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 out- 

 side 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 grad- 

 ual 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, sepa- 

 rated 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 cen- 

 ter ; 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 di- 

 vided, 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 



