"I can't believe it. Why, the girl's black as your hat."
"That's why they engaged her, in my opinion. It made the trick easier. A black face is a good disguise. But I'm going to be sure about it."
"How?"
"I'm going to see whether the colored girl is in the flat."
"How can you get in?"
"I'm going down the air shaft. The servant's room opens on that shaft. They'll have made her go in there so that her light won't show, as it would if she were in the kitchen."
Nick went to an engine-house near by, where he secured a coil of knotted rope.
He wished to make his investigations secretly, so as not to put Jones on his guard. It would not have been safe to get into the flat by the ordinary methods.
By using the fire escape of the building next door to the flat house, Nick got to the roof.
The top of the air shaft was covered with a framework, in which large panes of glass were set.