18 
The late Dr. Jenner 
when they feel no cold blast to benumb them, and when the 
common food with which they are supported, is distributed 
through the air in the greatest abundance. At such a time, 
what can be the inducement to them and their young ones, 
which have but just began to enjoy the motion of their wings, 
and play among the sun-beams, to take this dreary plunge ? 
And how is the office of respiration to be performed during 
the nine months watery residence ? The structure of the 
lungs of birds, differs not essentially from that of quadrupeds, 
and therefore all communication with the atmosphere being 
cut off from the first moment of submersion, the possibility 
of a bird living nine months, or indeed as many minutes 
under water, appears to be totally irreconcilable with the 
nature of their structure. I have taken a swift about the 
10th of August, which may be considered as the eve of its 
departure, and plunged it into water ; but like the generality 
of animals which respire atmospheric air, it was dead in two 
minutes. 
The late Doctor Beddoes has thrown out a supposition, 
that by frequent immersion in water, the association between 
the movements of the heart and lungs might perhaps be de- 
stroyed, and that an animal might be inured to live commo- 
diously for any time under water. As this will probably give 
new vigour to the languid system of the advocates for the 
submersion of birds, I think it incumbent upon me to men- 
tion it. 
Though we frequently see the swallow and the martin 
sprinkle and splash themselves as they glide over the sur- 
faces of ponds and rivers, yet we never see them dip under for 
a single moment ; indeed a few plunges would so moisten 
