{HEAD ~ Apparatus} 17 wherein {TAIL ~ the included angle} of the tapering section is at least twice the angle whose tangent equals the static coefficient of friction between the test contact member and the test probe 
wherein
{ HEAD ~ Apparatus } 17 wherein { TAIL ~ the included angle } of the tapering section is at least twice the angle whose tangent equals the static coefficient of friction between the test contact member and the test probe
HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH