WAGTAILS. 347 



study, and thus though, like the flint and steel, the 

 artificial systems did not smelt the ore and obtain the 

 metal, yet, like them, they, by their collision, struck 

 the spark that lit the furnace. 



Of the wagtails, properly so called, there are three ; 

 the pied, the grey, and the yellow. They are all of 

 the same size and weight as the nightingale, only a 

 little longer in the wings and the tail ; and though 

 they are all, to a certain extent, migratory, there is 

 only one that regularly leaves the country; yet from 

 their mode of feeding, the others are compelled to mi- 

 grate from place to place with the season, unless in 

 districts where the banks of the rivers are never 

 wholly frozen, and there they may be met with all the 

 year. The most widely diffused one is 



THE PIED WAGTAIL. 



This is sometimes called the black wagtail, and 

 sometimes the white. Linnseus chooses the latter 

 name (motadlla alba), and indeed it matters little 



