C J»* I 
while he draws his Breath thro' the aforementioned 
Tube, and the Air from c; by which Contrivance 
he not only draws continually cool and frcfh Air as 
long as any is in the Bell, but occafions at the fame 
time a Circulation, which is fo neceffary to the very 
Being of Air, (efpecially in a comprefs'd State) and 
its Prefervation for the ufe of Animals, which I have 
found to be of great Confequence; and fo much 
the more neceffary, as any body who has been in a 
Diving Bell for a long Time, without any new Sup- 
plies of Air, and has been reduc'd to the laft Ex- 
tremity of breathing in the lame, will agree with 
me, that when at fuch a Time the Bell begins to be 
haul'd up, and by that means the comprefs'd Air al- 
low'd to expand and be put into Motion never fo little, 
the Man receives, as it were, a new Life, and incre^ 
dible Comfort and Eafe. 
Again, when, in Coal-pits, Levels are drove in the 
Coal or thro' Dykes, the Air of the Level or Adits 
growing hot by the Breath and Sweat of the Hewers 
and Workmen for want of a Circulation of the Air; 
I have found it to be an excellent Remedy, to place 
along the fide of the Drift or Adit, a fquare wooden 
Box, open at both Ends, laid from the Place where 
the Air is cool and good, reaching as far, by joining 
one Box clofe to another, as where the Work is car- 
ried on. Thus, by this fimple Contrivance, a Circu- 
lation of Air is obtain'd, and fometimes to that De- 
gree, that when a Candle is held at the End of the 
Box where the cool Air enters, the Flame is driven 
out by the Current of cold Air entring and circulating 
thro' the Box. 
By which Experiment I am apt to think, that tho' 
the Diver fhould not keep the End of the flexible Tube 
r ~ "" in 
