468 Remarks on the 
north. This bird appears in the neighbour- 
hood of Senegal on the 6th of October; and 
has been seen as Jate as February in the same 
country. It is said to arrive at Athens, in lat. 
37° 25’, on the 18th of February; at Rome, 
in lat. 41° 45’, on the 22d of the same month; 
at Piacenza, in lat. 45°, March 20th, A. D. 
1738; at Tzaritzin, in lat. 48°30’, April 4th; 
in the late spring of 1793, at Catsfield, Jat. 
, April 14th, from a mean of twenty ob- 
servations; at Stratton, lat. 52° 45’, April Sth, 
from a mean of twenty observations; at Ken- 
dal, lat. 54° 20’, April 17th, from a mean of 
twenty-three observations ; at Upsal, lat. 59° 
30’, May 9th, from one observation. 
This route of the swallow towards the arctic 
circle, shews that the bird does not rely on its 
agility, and loiter in the torrid zone longer 
than is necessary. Onthe contrary, it travels 
slowly from climate to climate, until the sun 
isin 17 or 18 degrees of northern declination, 
and spring has made considerable advances in 
the ungenial climate of Sweden. One ano- 
maly occurs in the vernal progress of the 
swallow, which deserves the attention of the 
naturalist, because the circumstance when 
properly understood, shews how attentive the 
bird is to the local causes, which retard the 
spring in certain districts. The swallow ap- 
