second coil means for electromagnetically sensing relative proximity and up and down displacement of said projectile in terms of {HEAD ~ currents} induced by {TAIL ~ the mechanical motion} of the said projectile 
induced by
second coil means for electromagnetically sensing relative proximity and up and down displacement of said projectile in terms of { HEAD ~ currents } induced by { TAIL ~ the mechanical motion } of the said projectile
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH