3i6 



THE POPULAR SCIENCE MONTHLY. 



the Northern Hemisphere though very unequally, avoiding those spots 

 unfavorable to them. In this distribution they seem to have been 

 somewhat influenced by man, though owing him no other favors than 

 the incidental help of railroad-cuttings and sand-pits which have in- 

 creased the sites suitable for their nests and enabled them to spread 

 inland. 



It is one of the earliest birds to arrive in the spring, appearing in 

 Old England during the last week in March, and in New England 

 early in May, many passing on to the shores of the Arctic Ocean, 

 where Richardson, at the mouth of the Mackenzie, and Dall, on the 

 Yukon, found them breeding in immense numbers. In these high lati- 

 tudes its summer is necessarily a brief one, and September finds them 

 back again picking up their congeners for company on the southward 

 journey. 



Where these and other swallows spend the winter was a hotly- 

 debated question among ornithologists at the beginning of the pres- 

 ent century ; some afiirming that they migrated with the sun, while 

 others, believing it impossible that such small and delicate birds could 

 endure the great fatigue and temperatures incident to such a migra- 



