The invention is based on the recognition that an extremely rigid construction of the measuring cell is not necessary, provided that {HEAD ~ the compensation} of {TAIL ~ the exterior pressure variations} is carried out with sufficient accuracy 
of
The invention is based on the recognition that an extremely rigid construction of the measuring cell is not necessary , provided that { HEAD ~ the compensation } of { TAIL ~ the exterior pressure variations } is carried out with sufficient accuracy
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH