54 PROTO-BATHYSPHERES 



will not perhaps be unto these so necessary, to have the air 

 for breathing so pure and defecated as is required for 

 others. 



"But further, there are in this case these three things 

 considerable. 



"i. That the Vessel it self should be of a large capacity, 

 that as the air in it is corrupted in one part, so it may be 

 purified and renewed in the other: or if the meer refriger- 

 ation of the air would fit it for breathing, this might be 

 somewhat helped with bellows, which would cool it by 

 motion. 



"2. It is not altogether improbable, that the lamps or 

 fires in the middle of it, like the reflected beams in the 

 first Region, Rarefying the air, and the circumambient 

 coldness towards the sides of the Vessel, like the second 

 Region, cooling and condensing of it, would make such a 

 vicissitude and change of air, as might fit it for all its 

 proper uses. 



"3. Or if neither of these conjectures will help, yet 

 Mersennus tells us in another place, that there is in France 

 one Barricus a Diver, who hath lately found out another 

 art, whereby a man might easily continue under water 

 for six hours together; and whereas ten cubical feet of 

 air will not serve another Diver to breathe in, for half an 

 hour, he by the help of a cavity, not above one or two 

 foot at most, will have breath enough for six hours, and 

 a lanthorn scarce above the usual size to keep a candle 

 burning as long as a man please, which (if it be true, and 



