a force measurement device for obtaining a measurement indicative of the frictional force resisting {HEAD ~ movement} of {TAIL ~ the sample} as it is moved in said first direction 
of
a force measurement device for obtaining a measurement indicative of the frictional force resisting { HEAD ~ movement } of { TAIL ~ the sample } as it is moved in said first direction
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH