Firstly, due to {HEAD ~ the downwardly reentrant attitude} of tube 22, the exiting soap film solution passes downwardly and outwardly of tube 22 and cannot flow back to {TAIL ~ the sensor assembly} 20 
Firstly , due to { HEAD ~ the downwardly reentrant attitude } of tube 22 , the exiting soap film solution passes downwardly and outwardly of tube 22 and can not flow back to { TAIL ~ the sensor assembly } 20
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH