Since incision 11 is deeper than {HEAD ~ the knife depth L}, there is also lubricant which is carried beneath the knife face in the region 20 contacted by the bottom of the incisions 11 between {TAIL ~ the log} and the knife 
Since incision 11 is deeper than { HEAD ~ the knife depth L } , there is also lubricant which is carried beneath the knife face in the region 20 contacted by the bottom of the incisions 11 between { TAIL ~ the log } and the knife
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH