474 PHILOSOPHICAL TRANSACTIONS. [anNO iS/O. 



pumping out of the glass, yet before the first minute was quite ended, she gave 

 manifest tokens of being much disordered; and the operation being continued 

 a while longer, she grew so much worse, that several convulsive motions which 

 she fell into before a second minute was expired, obliged us to let in the air 

 upon her, whereby she quickly recovered. 



N. B. I determine not whether it be proper in this place to add, that when 

 the receiver was pretty well exhausted, the included bird appeared to the spec- 

 tators manifestly larger than before air was withdrawn, especially about the 

 crop, though that was very turgid before. And to manifest, that in this duck, 

 as in the former, the convulsions that used to be immediately followed by death, 

 proceeded from the withdrawing of the ambient air, and not from the clogging 

 of it ; we kept the same duckling in the same receiver very close to keep out 

 all external air, and to keep in the excrementitious steams of her body for 

 above six minutes, without perceiving her to grow sick upon her imprison- 

 ment ; which yet lasted above thrice the time that sufficed to reduce her in 

 the absence of the air to a gasping condition. 



N. B. It not being intended, that ducks and other water-fowl should, any 

 more than other birds, live in an exceedingly rarefied air, but only be able to 

 continue upon occasion a pretty while under water, it may suffice that the 

 contrivance of those parts, which relate to respiration, be so far fitted for the 

 purpose, as we shall see it when we come to the tenth title. 



The Second Title. 

 Of the Phcenomena afforded by Fzpers included in an Exhausted Receiver. 



Considering that vipers are animals endowed with lungs (though of a differ- 

 ent structure from those of men, dogs, cats, birds, &c.) and that their blood 

 is actually cold ; I thought it might, upon both those accounts, be very well 

 worth trying what effect the withdrawing and absence of the air would have 

 upon animals so constituted. I therefore made divers trials, some of which did 

 not displease me ; but I know not by what misfortune the memorials of them 

 were lost, except two or three, which I shall here subjoin though imperfect. 



Exp. I. — Jan. 2, 1662-3. We included a viper in a small receiver, and 

 as we drew out the air, she began to swell, and afforded us these phaenomena. 

 1 . It was a good while after we had left pumping, ere the viper began to swell 

 so much as to be forced to gape, which afterwards she did. 2. That she con- 

 tinued, by our estimate, above 2^ hours in the exhausted receiver without giv- 

 ing clear proof of her being killed. 3. That after she was once so swelled, as 

 to be compelled to open her jaws, she appeared slender and lank again, and 



