{TAIL ~ A light source} 14 wherein {HEAD ~ said helical portion} turns through an angle of at least about 720° 
{ TAIL ~ A light source } 14 wherein { HEAD ~ said helical portion } turns through an angle of at least about 720 °
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH