(2CI3) 
gave manifeft tokens of being much difordered ^ and the opera- 
Xion being continued a while longer , flie grew fo much worfe^ 
that feverai convulfive motions , (he fell into before a fecond mi- 
nute was expired, obliged us to let in the Air upon her ^ whereby 
(he quickly recovered* 
NB. I determine notjwhether it be proper in this place to add, 
that when the Receiver was pretty well exhaufted, the included 
Bird appeared to the Speflrators manifeftly biggerj than before the 
Air was withdrawn, efpecially about the crop, though that was 
very turgid before. And to manifeft, that in this Duck, as in the 
former, the convulfions, thatufedto be immediately followed 
by Death, proceeded from the withdrawing of the ambient Air, 
and not from the of it 5 we kept the fame Duckling in 
the lame Receiver very clofe, to keep out all external Air, and to 
keep in the excrementitious fteams of her body for above 6 min. 
without perceiving her to grow fick upon her imprifonment^ 
which yet lafted above thrice the time, that lufBced to reduce her 
in the abfence of the Air to a gafping condition, 
NB* It not being intended, that Ducks and other water- Fowl 
fhould any more than other Birds live in an exceeding rarifiedAir, 
but only be able to continue uponoccafion a pretty while un- 
der water>it may fuffice^that the contrivance of thofe parts,which 
relate to Refpiration , be fo far fitted for thepurpofe, as Vi^e (hall 
fee it is when we come to the Temh Title. 
The IL Title. 
Of the Th£ftomena aff^orded hj Vipers iticludedin anExhaufled 
Receiver. 
COnfidering that Vipers are Animals endowed with Lurgs 
(though of a differing ftrudlurefrom thofe of Men , Dogs, 
Cats, Birds, &c* ) and that their bloud is , asto fenfe , aftually 
«old 5 I thought, it might upon both thofe accounts be very well 
worth trying 3 what effed: the withdrawing and abfence of the 
Air would have upon Animals fo conftituted. I therefore made 
divers tryals,fome of which did not difpleafe me^ but I know 
not by what misfortune the memorials of them were lolt, except 
two or three (which were not per feft,) that I (hall here fubjoine. 
Experiment the l. 
We included a Viper in a fmall Receiver, and as 
we drew out the Air^fhe began to fwell, and afford- 3 
edus thefePhsenomena. S 2 I, It 
