78 BRITISH BIRDS. 



actions ; he observes, concludes, and never explains. Man has, besides this, 

 the logic of signs ; he observes and explains the visible series by an invisible 

 series. The one has knowledge of particular facts ; the other a knowledge 

 of general facts. The knowledge of the one is fixed ; that of the other, 

 facultative." 



2. What makes the first bird move ? 

 In reply to this, I observe there is no first bird. Wlien a flock of 

 Starlings of many thousands hear a gun, fear causes them to start : query, 

 which is the first bird ? The action is simultaneous. I might as well be 

 asked, when (as often is to be seen on the south downs) a flock of 

 sheep are driven to feed, what makes the first sheep move into the clover ? 

 There is none : hunger moves the flock. But if the question is, what makes 

 a number of birds travel at once ? then I say, one of the various causes 

 enumerated in the reply to question 1. 



3. How do they find their way ? 



This is much more difiicult ; and a satisfactory answer cannot be given. 

 I can only hope to throw a little light upon the subject. But, in the first 

 place, though they do find their way as a rule, they sometimes do not. Many 

 instances of lost birds have come under my observation ; and exceedingly 

 frightened they are, weak and starved usually, very much like other animals 

 under similar circumstances. If any one supposes that birds have a super- 

 natural and extraordinary method of finding their way, of such a mysterious 

 kind as has often been ascribed to dogs and cats, it certainly shows a very 

 lively imagination, a soaring into the realms of fancy too much for my com- 

 prehension ; in short, it is directly in violation of Comte's first law of 

 Primary Philosophy and Rule XV. of Lewes, viz. "Always to prefer the 

 simplest hypothesis compatible with the observed facts " (' Problems of Life 

 and Mind,' vol. i. p. 106). 



It is a mistake to suppose that in ordinary cases there is great fatigue 



