Each of the individual discs can be actuated, with {HEAD ~ the interposition} of {TAIL ~ a stepping mechanism}, via a push button which is adjacent to the viewing windows 
Each of the individual discs can be actuated , with { HEAD ~ the interposition } of { TAIL ~ a stepping mechanism } , via a push button which is adjacent to the viewing windows
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH