When the member is in its upper position, the ring is in the path of the air stream emitted by {HEAD ~ the fan} to produce {TAIL ~ a stream} of bubbles 
to produce
When the member is in its upper position , the ring is in the path of the air stream emitted by { HEAD ~ the fan } to produce { TAIL ~ a stream } of bubbles
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH