Briely stated, the present invention provides a bit assembley for a rotary drill having, a source of {TAIL ~ fluid} under {HEAD ~ pressure} 
Briely stated , the present invention provides a bit assembley for a rotary drill having , a source of { TAIL ~ fluid } under { HEAD ~ pressure }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD