{HEAD ~ a lever} having one end fixedly connected with {TAIL ~ said support shaft} and the other end pivotally connected with said shutter means, and 
{ HEAD ~ a lever } having one end fixedly connected with { TAIL ~ said support shaft } and the other end pivotally connected with said shutter means , and
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH