He is reading aloud to divert his mind.
Corporal Bavois is looking out of the window.

It must be dull music for him." The baron's voice would also be of advantage in overpowering any suspicious sound, should there be one.
And while Bavois worked, M.d'Escorval read, read, read.
He had completed the perusal of the entire paper, and was about to begin it again, when the old soldier, leaving the window, motioned him to stop.
"Half the task is completed," he said, in a whisper.

"The lower bars are cut." "Ah! how can I ever repay you for your devotion!" murmured the baron.
"Hush! not a word!" interrupted Bavois.

"If I escape with you, I can never return here; and I shall not know where to go, for the regiment, you see, is my only family.

Ah, well! if you will give me a home with you, I shall be content." Whereupon he swallowed a big draught of brandy, and set to work with renewed ardor.
The corporal had cut one of the second row of bars, when he was interrupted by M.d'Escorval, who, without discontinuing his reading, had approached and pulled Bavois's long coat to attract his attention.
He turned quickly.
"What is it ?" "I heard a singular noise." "Where ?" "In the adjoining room where the ropes are." Honest Bavois muttered a terrible oath.
"Do they intend to betray us?
I risked my life, and they promised me fair play." He placed his ear against an opening in the partition, and listened for a long time.