whereby a signal is transmitted from {HEAD ~ said first liquid container} to {TAIL ~ said second liquid container} by way of the liquid, and 
whereby a signal is transmitted from { HEAD ~ said first liquid container } to { TAIL ~ said second liquid container } by way of the liquid , and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH