476 



SCIENCE. 



[Vol. IY., No. 94. 



In glacial times the mountain plants of the arctic 

 zone descended to the valleys, and were distributed 

 with the glaciers toward the south. That this mi- 

 gration radiated from the north is shown by the fact 

 that not only do arctic species form almost half of 

 the plants in the snowy region of the Alps ; but also 

 the mountains of America, as well as of the Altai and 

 Himalayas, possess a large number of arctic forms 

 common also to the Swiss Alps. It is known that in 

 the tertiary and in the upper cretaceous periods a 

 number of species can be traced from Greenland as 

 far as Nebraska in America, and as far as Bohemia 

 and Moravia and southern Europe on the other side. 

 Similarly in the cretaceous period, in the tertiary, 

 and at the present time, Europe and North America 

 have in common a number of species which also 

 existed at that time in the arctic zone, and very evi- 

 dently had their origin there ; and hence the flora of 

 the far north has at all times exerted a great influence 

 on that of Europe. 



The endemic flora of the nival region originated 

 in the Alps, especially in the Monte Eosa chain. It 

 possessed its present features at the beginning of the 

 quaternary, and was distributed by means of the gla- 

 ciers into the valleys and the neighboring mountain 

 regions. 



THE DANISH INTERNATIONAL POLAR 

 STATION. 



The Danish polar station was at G-odthaab, Green- 

 land, — a little colony situated at the extremity of 

 a peninsula which separates the two large parallel 

 fiords, of Godthaab, and that, farther south, of 

 Ameralik. The station was erected on a little hill 

 of almost pure gneiss, twenty-six metres above the 

 level of the surround- 

 ing water. This place 

 was chosen both be- 

 cause it was the high- 

 est elevation in the 

 immediate neighbor- 

 hood and because the 

 gneiss appeared free 

 from iron ores. 



There were, in all, 

 five buildings. The 

 one farthest to the 

 south had two apart- 

 ments, of which that 

 to the east con- 

 tained the telescope 

 and the astronomical 

 apparatus. In the 

 other room were a 

 Robinson anemometer 

 and a recording anem- 

 oscope. North-east of this building were two for the 

 study of magnetic variations. East of this building 

 was a smaller one for the absolute determination of 

 terrestrial magnetism. The building farthest north 

 was the office; and there the barometers and the 

 Hagemann anemometer were placed, as well as a Mas- 



cart electrometer. Besides these, there was in the 

 open space a Wild shelter, covering the thermometers 

 to determine the temperature and humidity of the 

 air, a delicate hygrometer, and a Wild evaporimeter. 

 Three thermometers were placed vertically in holes in 

 the rock, at depths of sixteen, thirty-one, and sixty- 

 three centimetres. At the edge of the holes were small 

 iron pipes to prevent infiltration. The thermometers 

 were sheathed in wooden rods having the same diame- 

 ter as the holes. At the bottom of each hole was a lit- 

 tle mercury, which could penetrate to the thermome- 

 ter-bulbs through perforations made in the lower part 

 of the rods. Behind the shelter of the thermometers 

 were placed two thermometers whose bulbs were 

 buried fifteen and thirty-seven centimetres respec- 

 tively beneath the surface of the ground. At some 

 distance from the foot of the hill, two Hamberg ther- 

 mometers were placed at depths of one metre and one 

 and five-tenths metres. Besides the proposed obser- 

 vations, the parallaxes of a large number of auroras 

 were measured, the electricity of the air was studied, 

 and the temperature of the rocks, the soil, and the 

 water of the fiord, noted. 



In the early part of the autumn of 1882 the weather 

 was comparatively mild, south winds prevailing. It 

 was not till the last of September that it was cold 

 enough for a slight frost ; but the weather again mod- 

 erated under the influence of the south winds, which 

 lasted until the first days of October. From the 11th 

 of October the cold was maintained, almost without 

 interruption, until the 5th of March, 1883. During 

 all that interval the thermometer remained constant 

 ly below 0° C, except for some isolated days, and 

 then only for a short time. From the 23d of January 

 to the 13th of February the cold was the most intense 

 and persistent; so that even the south winds, and the 



very low barometrical 

 pressure during that 

 period, were powerless 

 to produce a change. 

 The greatest cold was 

 observed on the 9th of 

 February, with 24°.4 

 upon a slight eleva- 

 tion; but at the same 

 time it was found to be 

 26°. 7 in the low lands. 

 During the first part of 

 March the cold became 

 again very severe ; but 

 after the 5th of the 

 month the weather 

 moderated, and be- 

 came more variable. 

 It was only after the 

 middle of June that 

 the weather grew mild- 

 er. In July the heat was normal, and the winds from 

 the south ; but by the end of August frost appeared 

 again during the night. The greatest heat of 14°. 5 

 was observed on the 22d of June, during a tempest 

 from the south, at the same time that the thermome- 

 ter on the low lands attained 17° C. 



