INTRODUCTION. XV. 



degrees of heat and cold in the several climates of the world 

 whereby no country is destitute of inhabitants, and has given 

 them appetites for the productions of those countries whose 

 temperature is suited to their nature, as well as knowledge 

 and ability to seek and find them out." 



The migration of the Swallow tribe has been noticed by 

 almost every writer on the natural history of birds, and 

 various opinions have been formed respecting their dis- 

 appearance, and the state in which they exist during that in- 

 terval. Some naturalists suppose that they do not leave this 

 island at the end of autumn, but that they lie in a torpid 

 state till the beginning of summer, in the banks of rivers, in 

 the hollows of decayed trees, in holes and crevices of old 

 buildings, in sand banks and the like. That those which 

 have been left behind, as well as other birds of passage, as 

 soon as the cold weather sets in, fall into a torpid state, and 

 remain so till the return of warmth brings them out of it, are 

 facts which are now not doubted. But as to their passing 

 the winter immersed in water, and being found there in 

 " clusters, mouth to mouth, wing to wing, foot to foot," and 

 of their creeping down reeds to their subaqueous retreats, as 

 believed by Klein, as well as the similar description trans- 

 lated from Kami's Travels in North America, though these 

 marvellous narratives have been credited by some ornitho- 

 logists, yet nothing can exceed the absurdity of both ac- 

 counts.* 



* Extract of a letter from the Rev. Wm. Floyer Cornish, of Tot- 

 ness, Devon, dated April 10, 1826: "Being much interested in these 

 delightful little visitors (the summer migratory birds), and at the 

 same time very desirous to try whether I could keep them in health 

 during the winter, I will inform you of the result of my experiments. 



"I began with Nightingales, which I procured from London, and 

 have kept them in perfect health, and stout in song, for several 

 years ; those that I have had have been old birds, taken in the spring 

 soon after their arrival in England ; they seldom recommenced their 

 song till towards the end of the year, when they sang as finely as 

 those in their native woods. Having succeeded so well with ' the 



