Assertion: lens's diameter | /r/CapableOf | make small round hole
Facets:
value: in the centre of the cardboard
type: LOCATION
value: with a piercer
type: MANNER
Source sentences:
text: Make a small round hole in the centre of the cardboard with a piercer, and now remove to a darkened room; apply a candle close to the hole, and observe the illuminated patch visible upon the front combination; the diameter of this circle, carefully measured, is the actual working aperture of the lens in question for the particular stop employed.