In article ZPebf.991$Y97.815@trndny05,
George Patterson wrote:



I think you did very well. Sounds almost as good as if they had two separate
lung systems. Sounds to me sort of like a bagpipe; the lungs keep the sacs
full,
and they get a constant flow of oxygen from the sacs.

George Patterson
Drink is the curse of the land. It makes you quarrel with your
neighbor.
It makes you shoot at your landlord. And it makes you miss him.



The bagpipe is a good analogy, with the bird's airsacs as the bags, and
the drones and chanter of the pipe analogous to the lungs. Birds lungs
are rigid and don't expand and contract the way mammalian lungs do. All
the bellows work is done by the airsacs.

By the way, there is a piper's tune called "The Circular Breath".