( *77 ) 
IV. An Addition to the Defcription of the Art of 
Living under Water , publi/b’d in Phil. Tranfadh 
No. 349. (By the fame • 
I N No. 349. of the Pbilofophical TranfaBions , I 
did, as I fuppofe, fufficiently explain the Me- 
thod 1 had practiced and found effeftual to furnilh 
Air at any reafonable Depth under Water, and in 
any quantity defired, for the Subfifiance of men 
that fhall have occafion to work on Wrecks, or other- 
wife at the bottom, under a great Preffiure of Wa- 
ter. This I did by means of the Diving-Bell, which, 
being from time to time replenifhed with frefh Air, 
I had found fufficient to maintain five Men for near 
two Hours together in ten fathom Water, without 
the leaf! Hurt or Inconvenience. But the Bell be- 
ing not to be moved from place to place, but by 
moving the Vefiel from which it hung fufpended, 
was a great Impediment to the Work that was to bo 
done below } and therefore I bethought my felf how 
to enable the Diver to go out from the Bell to a 
confiderable difiance, and to ftaya fufficient time 
without it, with fuli freedom to aft as occafion fer- 
ved. And confidering that the Preffiure being grea- 
ter on the Surface of the Water in the Bell, than 
on any other Surface that was higher than it, the Air 
would by a Pipe pafs from the Bell into a Cavity of 
Air over that higher Surface j I concluded, that 
putting on a Cap of Lead made weighty enough to 
C c fink 
