Assertion: oboe's key | /r/CapableOf | extend the lowest register
Facets:
value: by lengthening the air column
type: MANNER
Source sentences:
text: In the upper and middle joints are the rings and keys covering lateral holes bored through the tube, by means of which the column of air, and consequently the wave length, may be shortened at will; the bell joint contains one or two keys normally open, which when closed extend the lowest register by lengthening the air column.