160 PNEUMATICS. 



manner as to be let down over its side without any 

 danger. Within, there was a circular seat for the 

 divers. To supply the bell with air under water, 

 two barrels, of about 63 gallons each, were made, 

 and cased with lead sufficient to make them sink 

 when empty; each having a hole in its lower part 

 to let in the water, as the air in them is condensed 

 in their descent, and to let it out again when they 

 were drawn up full from below. And, to a hole in 

 the top of the barrels, was fixed a hose, or hollow 

 pipe, well prepared with bees-wax and oil; which 

 was long enough to fall below the hole at the 

 bottom, being sunk with a weight appended: so 

 that the air in the upper part of the barrels could 

 not escape, unless the lower end of these pipes 

 were first lifted up. These air-barrels were fitted 

 with tackle proper to make them rise and fall 

 alternately, like two buckets in a well : in their 

 descent, they were directed, by lines fastened to 

 the under edge of the bell, to the man standing on 

 the stage to receive them ; who, by taking up the 

 ends of the pipes above the surface of the water in 

 the bell, gave occasion for the water in the barrels 

 to force all the air in the upper parts into the bell, 

 while it entered below, and filled the barrels. And, 

 as soon as one was discharged, by a signal given 

 it was drawn up; and the other descended, to be 

 ready for use. As the cold air rushed into the 

 bell from the barrel below, it expelled the hot air 

 (which was lighter) through the cock at the top, 

 which was then opened for that purpose. By this 

 method, air was communicated so quick, and in 

 such plenty, that the Doctor tells us, he himself 

 was one of five who were together at the bottom, 

 in nine or ten fathoms water, for above an hour 

 and a half at a time, without experiencing any ill 



