Whenever the force of gravity lessens, the second end of {HEAD ~ the beam or wire breaks contact} with {TAIL ~ the tube}, creating an open switch 
Whenever the force of gravity lessens , the second end of { HEAD ~ the beam or wire breaks contact } with { TAIL ~ the tube } , creating an open switch
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH