<span font='Helvetica 8'>As the Air is of <i>absolute Necessity</i> to Animal Life, so it is necessary
that it should be of a due Temporament or Consistence; not foul, by
reason that suffocateth; nor too rare and thin, because that sufficeth
not: with Examples of each of which, I shall a little entertain the
Reader. In one of <b>Mr. Hawksbee's Compressing Engines</b>, I closely shut
up a Sparrow without forcing any Air in; and in less than an Hour the
Bird began to pant, and be concerned; and in less than an hour and a
half to be sick, vomit, and more out of Breath; and in two hours time
was nearly expiring.

Another I put in and compressed the Air, but the Engine leaking, I
frequently renewed the Compressure; by which means, (although the Bird
panted a little after the first hour,) yet after such frequent
Compressures, and Immission of fresh Air, it was very little
concerned, and taken out seemingly unhurt after three hours.

After this I made two other Experiments in compressed Air, with the
Weight of two Atmospheres injected, the Engine holding tight and well;
the one with a Great Titmouse, the other with a Sparrow. For near an
Hour they seemed but little concerned; but after that grew fainter,
and in two Hours time sick, and in three Hours time died. Another
thing I took notice of, was, that when the Birds were sick and very
restless, I fancied they were somewhat relieved for a short space,
with the Motion of the Air caused by their fluttering, and shaking
their Wings, (a thing worth trying in the Diving-Bell,) I shall leave
the ingenious Reader to judge what the cause was of both the Birds
living longer in compressed, than uncompressed Air; whether a lesser
quantity of Air was not sooner fouled and rendered unfit for
Respiration, than a greater.</span>
