{HEAD ~ Apparatus} 36 includes a tube 37, having {TAIL ~ a pump} 38 at one end and gas entry pipes 39 and 40 shown for convenience as being at the other end 
{ HEAD ~ Apparatus } 36 includes a tube 37 , having { TAIL ~ a pump } 38 at one end and gas entry pipes 39 and 40 shown for convenience as being at the other end
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH