a first rotatable means for controlling {HEAD ~ the horizontal movement} of {TAIL ~ said cover} through Said linear means, 
of
a first rotatable means for controlling { HEAD ~ the horizontal movement } of { TAIL ~ said cover } through Said linear means ,
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH