334 NATURAL HISTORY 



desultory flight; swallows sweep over the surface of 

 the ground and water, and distinguish themselves by 

 rapid turns and quick evolutions ; swifts dash round in 

 circles; and the bank martin moves with frequent vacil- 

 lations like a butterfly. Most of the small birds fly by 

 jerks, rising and falling as they advance. Most small 

 birds hop; but wagtails and larks walk, moving their 

 legs alternately. Skylarks rise and fall perpendicularly 

 as they sing; woodlarks hang poised in the air; and 

 titlarks rise and fall in large curves, singing in their 

 descent. The whitethroat uses odd jerks and gesticu- 

 lations over the tops of hedges and bushes. All the 

 duck kind waddle ; divers and auks walk as if fettered, 

 and stand erect on their tails : these are the compedes of 

 Linnaeus. Geese and cranes, and most wild fowls, 

 move in figured flights, often changing their position. 

 The secondary remiges of Tringce, wild ducks, and some 

 others, are very long, and give their wings, when in 

 motion, a hooked appearance 1 . Dabchicks, moorhens, 

 and coots, fly erect, with their legs hanging down, and 

 hardly make any dispatch; the reason is plain, their 

 wings are placed too forward out of the true centre of 

 gravity ; as the legs of auks and divers are situated too 

 backward. 



LETTER XLIII. 



TO THE SAME. 

 DEAR SIR, SELBORNE, Sept. 9, 1778. 



FROM the motion of birds, the transition is natural 

 enough to their notes and language, of which I shall 

 say something. Not that I would pretend to under- 

 stand their language like the vizier, who, by the re- 



1 The elongated feathers are the tertials : the secondaries are short. 

 W.Y. 



