MIGRATION AND FLIGHT. 
87 
birds ; for when we take into consideration what has been said 
of their rapid flight, which would enable an Eagle in nine 
days, allowing him sixteen or seventeen hours for repose, to 
go round the world, there is nothing so very extraordinary in 
the journey of a Swallow from the shores of England to those 
of Sierra Leone in Africa, where a person, who resided there 
for seven years, constantly observed our three species, many 
of them remaining all the year, but their numbers much 
diminished from spring to autumn, when they were supposed 
to be absent, spending their summer in Europe. 
On looking at the map, it will be seen that without 
further peril by sea than simply crossing the short space of 
the British Channel and Straits of Gibraltar, (either of which, 
at their narrowest parts, even a barn-fed Sparrow might 
easily do in an hour or two,) a bird might make almost a 
direct course to Sierra Leone, a distance of about 3000 miles, 
which space a Swallow would without effort traverse in three 
days, including time for roosting at night, and which even a 
Sparrow could perform at leisure, and without the least 
fatigue, in less than a fortnight. The above calculation is 
made on the supposition that the airy travellers keep over 
the land as much as possible : but if the straightest course 
were preferred, they might, by crossing the Bay of Biscay, 
perform it in less time. And that Swallows do, at least 
occasionally, take this line we know, from the very curious 
fact of one settling on the rigging, and caught on board a 
vessel bound to the French port of Havre, beneath the wing 
of which was found a very small slip of paper, on which was 
written in French, “ The ship Armide, Captain Borgnet, going 
to Martinique, latitude 48° 33' north, longitude 10° 39' west.” 
On reference to the map, it will be seen that this point is 
nearly in a straight line, drawn from the Land’s End in 
England to the western coast of Africa. 
It might be supposed, taking place as these journeys do 
with Swallows twice in the year, that frequent opportunities 
would occur of seeing their arrival or departure in flocks, but, 
with the exception of straggling parties of ten or twelve at a 
time, few have been fortunate enough to see them either come 
