What do you say to the handkerchief full of blood, and the red mark of the hand on the wall?
You have seen the stain on the wall, but I have only seen the handkerchief." "Bah!" cried Rouletabille, "the murderer was wounded in the hand by Mademoiselle Stangerson's revolver!" "Ah!--a simply instinctive observation! Take care!--You are becoming too strictly logical, Monsieur Rouletabille; logic will upset you if you use it indiscriminately.

You are right, when you say that Mademoiselle Stangerson fired her revolver, but you are wrong when you say that she wounded the murderer in the hand." "I am sure of it," cried Rouletabille.
Fred, imperturbable, interrupted him: "Defective observation--defective observation!--the examination of the handkerchief, the numberless little round scarlet stains, the impression of drops which I found in the tracks of the footprints, at the moment when they were made on the floor, prove to me that the murderer was not wounded at all.

Monsieur Rouletabille, the murderer bled at the nose!" The great Fred spoke quite seriously.

However, I could not refrain from uttering an exclamation.
The reporter looked gravely at Fred, who looked gravely at him.

And Fred immediately concluded: "The man allowed the blood to flow into his hand and handkerchief, and dried his hand on the wall.