142 MY NATURE NOTEBOOK. 



can cross tracts of ocean, when the chill of coming 

 winter drives insect life from the upper air to earth. 

 Then, looking at the little willow-wren, fluttering 

 among the branches of a larch, carefully examining 

 one twig before it flits to the next, one is inclined to 

 wonder how so trivial a thing crosses seas and conti- 

 nents twice a year. But the wind is a constant factor, 

 and a very great factor, in the journey of both. Thus, 

 if the wind blows from the north only at the rate of 

 fifty miles an hour, the swift, flying sixty miles an 

 hour, will only have achieved a hundred and ten 

 miles, while the willow-wren, with thirty miles an 

 hour, would have flown eighty ; and, of course, the 

 stronger the wind the less would be the proportionate 

 difference. A balloon cannot fly at all ; yet if we 

 could steer a balloon and alight with certainty and 

 safety whenever we wished, who would think any- 

 thing of travelling to Africa by balloon ? We should 

 only have to ascend when the north wind blew, and 

 rest when contrary winds prevailed ; and this is what 

 the little warbler is able to do, because the contrary 

 winds that is, the warm south winds bring out 

 plenty of insects for him to feed upon. 



A PUGNACIOUS ATOM. 



And in giving the willow-wren only thirty miles 

 an hour, we may do him an injustice, for you may 

 often see him exhibiting a pretty turn of speed. He 

 has a big heart in his little body, and his delicacy of 

 outline covers a remarkably pugnacious character. 

 For no reason whatever, apparently, he will chase 

 any passing bird, and, small as he is, there are few 



