OF SELBORNE. 
for ages, being caft up in pellets out of the crops of many genera- 
tions of inhabitants. For owls caft up the bones, fur, and feathers, 
of what they devour, after the manner of hawks. He believes, 
he told me, that there were bufhels of this kind of fubftance. 
When brown owls hoot their throats fwell as big as an hen's egg. 
I have known an owl of this fpecies live a full year without any 
ivater. Perhaps the cafe may be the fame with all birds of prey. 
When owls fly they ftretch out their legs behind them as a balance 
to their large heavy heads . for as moft nofturnal birds have large 
eyes and ears they muft have large heads to contain them. Large 
eyes I prefume are neceflary to colled: every ray of light, and 
large concave ears to command the fmalleft degree of found 
or noife. I am, he. 
It will be proper to premife here that the fixteenth, eighteenth, twentieth, 
and twenty-firft letters have been publifhed already in the Philofophical Tranfac- 
tions : but as nicer obfervation has furnifhed feveral corredions and additions, it is 
hoped that the republication of them will not give offence; efpecially as thefe 
fheets would be very imperfeft without them, and as they will be new to 
many readers who had no opportunity of feeing them when they made their firft 
appearance. 
The hirundlms are a moft inoffenfive, harmlefs, entertaining, 
fecial, and ufeful tribe of birds : they touch no fruit in our gar- 
dens ; delight, all except one fpecies, in attaching themfelves to 
our houfes ; amufe us with their migrations, fongs, and marvellous 
agility; and clear our outlets from the annoyances of gnats and 
other troublefome infefts. Some diftridts in the fouth feas, near 
X 2 Gu'uvpil, 
