d) measuring {HEAD ~ the flow} of air from {TAIL ~ said second compartment} through said outlet means; and 
from
d ) measuring { HEAD ~ the flow } of air from { TAIL ~ said second compartment } through said outlet means ; and
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH