BRITISH BIRDS. 
397 
are defcribed as fo clofely placed together, that it 
is difficult to walk without treading upon fome of 
them ; and it is faid that the fwarms of the old 
birds are fo prodigious, that when they rife into the 
air, they ftun the ear with their noife, and over- 
fhadow the ground like the clouds. * At the fmall 
ifle of Borea, Martin fays “ the heavens were dark- 
ened by thofe flying above our heads ; their excre- 
ments were in fuch quantity, that they gave a 
tincture to the fea, and at the fame time fuliied our 
boat and cloaths.” Befides this fmall ifle of Bo- 
rea, and St Kilda, noticed by Martin, Pennant and 
other writers mention the ifle of Ailfa in the Frith 
of Clyde ; the Stack of Souliskerry, near the Ork- 
neys ; the Skellig Ifles, off the coafl of Kerry, Ire- 
land ; and the Bafs Ifle, in the Frith of Forth. 
This lafl-mentioned ifle is farmed out at a confider- 
abie rent for the eggs of the various kinds of wa- 
ter-fowl with which it fwarms ; and the produce of 
the Solan Geefe forms a large portion of this rent ; 
for great numbers of their young ones are taken 
^ Martin, in his Hiflory of and Voyage to St Kilda, pub- 
liihed in 1698, fays “ the inhabitants of St Kilda take their 
meafnres from the flight of thefe fowls, when the heavens are not 
clear, as from a fure corapafs, experience Ihewlng that every tribe 
of fowls bend their courfe to their refpeftive quarters, though 
out of light of the ifle ; this appeared clearly In our gradual ad- 
vances ; and their motion being compared, did cxadly quadrate 
with our compafs/' 
