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 



