FIGS 2 and 4 show {HEAD ~ the arm} pivoted to two positions on opposite sides of {TAIL ~ the intermediate position} of FIG 3 which correspond to the shortening of one of the two cords 57 and the lengthening of the other 
FIGS 2 and 4 show { HEAD ~ the arm } pivoted to two positions on opposite sides of { TAIL ~ the intermediate position } of FIG 3 which correspond to the shortening of one of the two cords 57 and the lengthening of the other
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH