256 CLIMATOLOGY. 



and in the last week of this month the van flocks of snow-geese 

 are seen going southwards, having spent between eighty and 

 ninety days at their breeding stations. The laughing-geese 

 follow in a day or two ; but they pass on in autumn without any 

 of the delays that characterise their spring flights, which are 

 necessarily checked as often as a few cold days arrest the melt- 

 ing of the snow on the sea-coast. Drift ice obstructs the navi- 

 gation of the lake in some seasons till the first or second week 

 of August. 



In the last week of August, or in the beginning of Sep- 

 tember, snow falls, and by the 10th of the month the deciduous 

 leaves begin to drop. By the 18th, most of the birds which 

 breed in the district have migrated southwards, a few water- 

 fowl and the winter residents alone remaining. Between the first 

 appearance of vegetation, till the falling of the leaves of deciduous 

 trees, about a hundred clays elapse ; but although this may 

 be taken as the length of the season for the growth of plants, 

 some of the grasses continue to ripen their seeds till the be- 

 ginning of October, notwithstanding much severe frost before 

 that date. In ordinary seasons the frost sets in severely before 

 the end of September, and the seeds of carices and grasses, in- 

 stead of dropping off, are frozen hard in their glumes, and remain 

 hanging on the culm till next spring, when they drop off into a 

 soil prepared by the thaw for their reception. It is on these 

 grass seeds of the preceding year that the graminivorous birds 

 feed on their first arrival from the south. In October, when the 

 soil begins to freeze again, the summer thaw has penetrated 

 about twenty-one inches in the neighbourhood of Fort Franklin. 

 The small lakes are covered with ice by the 10th or 12th of the 

 month ; and, when that occurs, the last of the water-fowl depart. 

 By the 20th of the month the smaller trees are frozen through, 

 the larger ones remaining soft and moist in the centre. By the 

 end of the month, or early in November, the young ice, filling 

 the bays, puts an end to the navigation of the lake, after it has 

 continued open about sixty days. The centre of the lake does 

 not freeze over till late in December. 



