second retaining means adapted to hold said blades in any one of said positions whereby said springs urge the said stems into engagement with said second retaining means, and said helical springs are compressed to disengage said second retaining means to change {HEAD ~ the position} of {TAIL ~ said blades} 
of
second retaining means adapted to hold said blades in any one of said positions whereby said springs urge the said stems into engagement with said second retaining means , and said helical springs are compressed to disengage said second retaining means to change { HEAD ~ the position } of { TAIL ~ said blades }
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL