As he pulled it down one lonely bulb in the meeting-room brightened and cast a dim light in the musty, empty place.

It was evidently the only bulb in which the individual switch was turned on.

Norton went through the meeting-room and turned this off.

The place smelled for all the world like a school-room.
When he reached the ladder it was bathed in light.

Nick was pointing a shaft of dazzling brightness downward.