The Natural History of Selborne 213 



While I am talking of owls, it may not be improper to mention 

 what I was told by a gentleman of the county of Wilts. As they 

 were grubbing a vast hollow pollard-ash that had been the mansion 

 of owls for centuries, he discovered at the bottom a mass of 

 matter that at first he could not account for. After some examina- 

 tion he found that it was a congeries of the bones of mice (and 

 perhaps of birds and bats) that had been heaping together for 

 ages, being cast up in pellets out of the crops of many generations of 

 inhabitants. For owls cast up the bones, fur, and feathers, of what 

 they devour, after the manner of hawks. He believes, he told me, 

 that there were bushels of this kind of substance. 



When brown owls hoot, their throats swell as big as an hen's egg. 

 I have known an owl of this species live a full year without any water. 

 Perhaps the case may be the same with all birds of prey. When 

 owls fly they stretch out their legs behind them as a balance to their 

 large heavy heads, for as most nocturnal birds have large eyes and 

 ears they must have large heads to contain them. Large eyes I 

 presume are necessary to collect every ray of light, and large con- 

 cave ears to command the smallest degree of sound or noise. 



I am, &c. 



[It will be proper to premise here that the sixteenth, eighteenth, 

 twentieth, and twenty-first letters have been published already in 

 the " Philosophical Transactions " ; but as nicer observation has 

 furnished several corrections and additions, it is hoped that the 

 republication of them will not give offence ; especially as these 

 sheets would be very imperfect without them, and as they will be 

 new to many readers who had no opportunity of seeing them when 

 they made their first appearance.] 



The hirundines are a most inoffensive, harmless, entertaining, 

 social, and useful tribe of birds ; they touch no fruit in our gardens ; 

 delight, all except one species, in attaching themselves to our houses ; 

 amuse us with their migrations, songs, and marvellous agility; and 

 clear our outlets from the annoyances of gnats and other troublesome 

 insects. Some districts in the south seas, near Guiaquil,* are 



* See " Ulloa's Travels." 



