

200 THE NATURAL ‘HIS TORY 
cafe, in a river fo perpetually fithed as the Rives | 
Thames, the fifhermen mutt very frequently bl 
them up in their nets. 
} It has been obferved, that the twigs ‘upon ‘hich 
they have collected, generally die. 
ae They leave this country, or at leaft difappeat 
about the beginning of OGober; and it is fup- 
poled they generally depart in the night, pere 
haps to be lefs expofed to the attacks of birds of 
prey; and that they avail themfelves of a te 
vourable wind, which muft wonderfully facilitate _ 
their paflage: when we confider the velocity 
with which air balloons have been carried, mere-_ 
ly by the current of the air, at a little elevation, 
the difficulty of the migration of birds feems 
riituch leflened; and it has been obferved by 
Mr. Hebert, that Swallows, on their departure, 
rife into a higher region of the air. 
Inthe Iflands of Hieres, which are on the fourth. 
a coaft of France, where the weather is always tem 
perate, and a perpetual fpring is enjoyed, Swal 
lows have been feen all the winter; there they 
have found their infect food. They rooit upon 
“the orange trees, and injure that delicate plant. 
A Swallow has been employed like a Cartiet 
Pigeon; the female was taken from her nell 
to the place from which the intelligence was to be 
fent, ‘ahd a thread of a certain colour, and a cer-~ 
| tain 
beam tp pe ay 
Seg Re ee es z 
