Then he discovered a rusty bell pull and gave it a sharp tug.

The knob came off in his hand and he hurriedly thrust it back again into its place.

Evidently, that bell was solely for ornament.
He came to the conclusion that no one was at home and felt a guilty sense of relief in consequence.

But his conscience would not let him depart without another try, so he clenched his fist and gave the cracked door panel a series of tremendous thumps.

A thin black cat, which had evidently been asleep beneath the step, burst from its concealment and fled in frantic terror.