X 26 7 1 
fwallows, to enter into a very minute difcufilon of 
what may, or may not, be inferred from his obfer- 
vation according to his own narrative. 
I lhali firft however confidef the general argu- 
ments, from which it is fuppofed that birds of paflage 
periodically traverfe oceans, which indeed maybe 
almoft reduced to this Angle one, viz. we fee certain 
birds in particular feafons, and afterwards we fee 
them not ; from which data it is at once inferred, 
tjaat the caufe of their difappearance is, that they 
have crofted large tra&s of fea. 
The obvious anfvver to this is, that no welhattefted 
inftances can be produced of fuch a migration, as I 
fhall endeavour to fhew hereafter j but befides this 
convincing negative proof, there are not others want- 
ing- 
Thofe who fend birds periodically acrofs. the fea, 
being preffed with the very obvious anfwer I have 
before fuggefted, have recourfe to two fuppofitions, 
by which they would account for their not being 
obferved by feamen during their paffage. 
The firft is, that they rife fo high in the air that 
they become invifible * but unfortunately the rifing 
to this extraordinary height, or the falling from it, is 
equally deftitute of any ocular proof, as the birds 
being feen during their paffage. 
I have indeed converfed with fome people, who 
conceive they have loft fight of birds by their per- 
pendicular flight ; I muft own, however, that I have 
* It is well known that fome ornithologifts have even fup- 
pofed that they leave our atmofphere for that of the Moon. See 
Had. Mifc, Vol. II. p. 561. 
M m % 
always 
