THE NORTH POLAR BASIN. 389 



vilifige sallies forth to peg out with rows of birch trees the wiuter road 

 down the river to the next village, for which he is responsible, he has 

 frequently to deviate widely from the direct course in his efforts to 

 choose the smoothest ice, and find a chaunel between the hummocks 

 that continually block the way. 



The date upon which winter resumes his sway varies greatly in differ- 

 ent localities, and probably the margin between an early and a late 

 season is considerable. In 1876, Capt. Wiggins was frozen up in winter 

 quarters on the Yenisei, in latitude 004°, on October 17. In 1878 Capt. 

 Palander was frozen up on the coast 120 mUes west of P>ering Strait, in 

 latitude G7f°, on September 28. 



The sudden arrival of summer on the Arctic Circle appears to occur 

 nearly at the same date in all the great river basins, but the number 

 of recorded observations is so small that the slight variation may pos- 

 sibly be seasonal and not local. The ice ou the Mackenzie River is 

 stated by one authority to have broken up ou May 13, in latitude 02°, 

 and by another on May 9 in latitude 07°. If the INIackenzie breaks up 

 as fast as the Yenisei — that is to say at the rate of a degree a day, 

 an assumption which is supported by what little evidence can be found — 

 then the difference between these two seasons would be nine days. My 

 own experience has been that 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 nuich importance must not be attached to the dates. 



According to the Challenger tables of isothermal lines, the mean 

 temperatures of January and July ou the Arctic Circle in the valleys of 

 the Mackenzie and the Yenisei scarcely differ, the summer tempera- 

 ture in each case being about 55° F., and that of winter — 25° F., a dif- 

 ference of 80° F. 



On the American side of the Polar Basin summer comes almost as sud- 

 denly as it does ou the Asiatic side, but tlie 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 rain-fall. There is only one large river Avhich empties itself into the 

 Arctic Ocean on the American side, the Mackenzie, with which maybe 

 associated the Saskatchewan, which discharges into Hudson Bay far 

 away to the south. The basin of the Mackenzie is estimated at 590,000 

 S(iuare miles, wliilst 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 feet deep, so that the 

 spring tlood 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 



