After writing a few lines (too far away from my peep-hole to give me a chance of reading over his shoulder), he leaned back in his chair, and amused himself by humming the tunes of popular songs.

I recognized "My Mary Anne," "Bobbin' Around," and "Old Dog Tray," among other melodies.
Whether these do or do not represent secret signals by which he communicates with his accomplices remains to be seen.

After he had amused himself for some time by humming, he got up and began to walk about the room, occasionally stopping to add a sentence to the paper on his desk.

Before long he went to a locked cupboard and opened it.

I strained my eyes eagerly, in expectation of making a discovery.