He was not long examining it, and he went right through it out into the street on which the house would face when it was finished.

He looked up and down it, and began to retrace his footsteps.
"I've seen all I want to see out here.

We may as well go back to the house," he said to the Duke.
"I hope you've seen what you expected to see," said the Duke.
"Exactly what I expected to see--exactly," said Guerchard.
"That's as it should be," said the Duke.
They went back to the house and found M.Formery in the drawing-room, still engaged in the process of reconstruction.
"The thing to do now is to hunt the neighbourhood for witnesses of the departure of the burglars with their booty.

Loaded as they were with such bulky objects, they must have had a big conveyance.

Somebody must have noticed it.