The heated air then passes through the flow of grain in {TAIL ~ each} of the columns 26 so as to heat and remove moisture from {HEAD ~ the grain} 
The heated air then passes through the flow of grain in { TAIL ~ each } of the columns 26 so as to heat and remove moisture from { HEAD ~ the grain }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD