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