128 Zoological Society :— 
However striking the result of such a comparative review may be, 
one question will always present itself, namely :—Whether it be pos- 
sible for a bird to sustain an uninterrupted flight sufficient to carry 
it across the wide expanse of the Atlantic. I am convinced that this 
is possible, and shall endeavour to prove such possibility. 
This purpose necessitates a measure for the rate of locomotion of 
a bird through the atmosphere. Fora long time I vainly endeavoured 
to obtain reliable data upon which to found an estimation of the rate 
of flight of birds—when at last I hit upon a passage in Yarrell’s 
‘ British Birds,’ ii. p. 295, where, speaking of the Carrier Pigeon, he 
mentions the fact of one of these birds having performed a flight of 
150 miles in an hour anda half: it was on the 24th of June 1833; 
the Pigeon flew from Rouen to Ghent ; sixteen others flew the same 
distance in two hours and a half. 
Wonderful as this instance of swiftness of the flight of a bird may 
appear, it certainly is still surpassed by birds when on their period- 
ical migrations; for the above feat was accomplished by an indivi- 
dual hatched and reared in at least semi-confinement, whose powers 
of flight consequently could not be nearly so well developed as in a 
bird grown up wild and free, which nearly every hour of its life has 
to depend on the utility of its wings, either for the purpose of over- 
taking its prey, or for that of escaping from being caught. 
Laying down, therefore, 100 geographical miles per hour as the 
rate of flight of birds during distant migration, one keeps—after 
the above—quite within safe bounds; and at this rate the 1600 
geographical miles from Newfoundland to Ireland would be effected 
in ‘sixteen hours. No ornithologist will doubt for a moment the 
capability of a healthy bird to sustain a flight of that duration. 
During the long summer days, many of the Hirundinide are on the 
wing for as long a period; and although their flight may be inter- 
rupted by occasional rests of very short duration, it is performed in 
the lower, less buoyant atmosphere, and consists of so many evolu- 
tions, that most decidedly it must on the whole be much more tiresome 
than the straight path in the pure upper regions of a bird bent on 
the performance of one long pilgrimage. 
Even supposing that birds become exhausted before accomplishing 
the passage across the ocean, observations I have made in the vici- 
nity of this island have fully convinced me that small birds, such as 
Thrushes, Buntings, Finches, &c., are able to rest on the sea—even 
when a little in motion—and afterwards to resume and pursue their 
flight with fresh vigour. Of this I shall give the particulars further — 
on, but for the present return to the above question, by giving an 
instance of endurance on the wing of a species which, with pretty 
good certainty, may be said every spring to perform in the period of 
one night a flight of more than 1200 geographical miles—namely, 
from Eeypt to Heligoland,—the bird in question being a particular 
form of Blue-throated Warbler, Sylvia exrulecula, Pallas. 
This pretty little bird, noted not at all either for rapidity or great 
endurance of flight, has its summer quarters in the high northern 
latitudes of Sweden, Finland, and Siberia, whereas during the winter 
