TRANSACTIONS OF SECTION E. 829 



the ice of the Pechora breaks up ten days before that of the Yenisei, but as I 

 have only witnessed one such event in each valley too much importance must not 

 be attached to the dates. 



According to the ' Challenger ' tables of isothermal lines the mean temperatures 

 of January and July on the Arctic Circle in the valleys of the Mackenzie and the 

 Yenisei scarcely ditfer, the summer temperature in each case being about 55° F.^ 

 and that of winter -25° F., a difference of 80° F. 



On the American side of the Polar Basin summer comes almost as suddenly as 

 it does on the Asiatic side, but the change appears to be less of the nature of a 

 catastrophe. The geographical causes which produce this result are the smaller 

 area of the river basins and the less amount of rainfall. There is only one large 

 river which empties itself into the Arctic Ocean on the American side, the 

 Mackenzie, with which may be associated the Saskatchewan, which discharges into 

 Hudson Bay far away to the south. The basin of the Mackenzie is estimated at 

 690,000 square miles, whilst that of the Yenisei is supposed to be exactly twice 

 that area. The comparative dimensions of the two summer floods are still more 

 diminished by the difference in the quantity of snow. 



The snow in the Mackenzie basin is said to be from 2 to 3 feet deep, whilst that 

 in the Yenisei basin is from 5 to 6 feet deep, so that the spring flood in the latter 

 river must be about five times as large as that of the former. 



Another feature in which the basin of the Mackenzie differs from those of the 

 rivers in the Arctic regions of the Old World is the number of rapids and lakes- 

 contained in it. The ice in the large lakes attains a thickness at least twice as- 

 great as that of the rapid stream, and consequently breaks up much later. In the 

 Great Slave Lake the ice attains a depth of 6 to 7 feet, and even in the Athabaska 

 Lake, in latitude 58°, it reaches 4 feet. The rapids between these two lakes 

 extend for 15 miles. The ice on the river breaks up a month before that on. 

 the lakes, so that the drainage area of the first summer flood is much restricted. 



The arrival of summer in the Arctic regions happens so late that the inex- 

 perienced traveller may be excused for sometimes doubting whether it really i* 

 going to come at all. When continuous night has become continuous day without 

 any perceptible approach to spring an alpine traveller naturally asks whether he 

 has not reached the limit of perpetual snow. It is true that here and there a few 

 bare patches are to be found on the steepest slopes, where most of the snow has 

 been blown away by the wind, especially if these slopes face the south, where 

 even an Arctic sun has more potency than it has elsewhere. It is also true that 

 small flocks of little birds — at first snow-buntings and mealy redpoles, and later 

 shore larks and Lapland buntings — may be observed to flit from one of these bare 

 places to another looking for seeds or some other kind of food, but after all evi- 

 dently finding most of it in the droppings of the peasants' horses on the hard 

 snow-covered roads. The appearance of these little birds does not, however, give 

 the same confidence in the eventual coming of summer to the Arctic naturalist as 

 the arrival of the swallow or the cuckoo does to his brethren in sub- Arctic and sub- 

 tropic climates. The four little birds just mentioned are only gipsy migranta 

 that are perpetually flitting to and fro on the confines of the frost, continually 

 being driven south by snowstorms, but ever ready to take advantage of the 

 slightest thaw to press northwards again to their favourite Arctic home. 

 They are all circumpolar in their distributions, are as common in Siberia as 

 in Lapland, and range across Canada to Alaska as well as to Greenland. In sub- 

 Arctic climates we only see them in winter, so that their appearance does not in the 

 least degree suggest the arrival of summer to the traveller from the south. 



The gradual rise in the level of the river inspires no more confidence in the 

 final melting away of the snow and the disruption of the ice which supports it. 

 In Siberia the rivers are so enormous that a rise of 5 or 6 feet is scarcely per- 

 ceptible. The Yenisei is three miles wide at the Arctic Circle, and as fast as it 

 rises the open water at the margin freezes up again and is soon covered with 

 the drifting snow. During the summer which I spent in the valley of the Yenisei 

 we had 6 feet of snow on the ground until the first of June. To all intents 

 and purposes it was mid-winter, illuminated for the nonce with what amounted 



