I then learned that the youth was one of Larsan's assistants and had been charged by him to watch the going and coming of travellers at the station of Epinay-sur-Orge.

Larsan neglected nothing in any case on which he was engaged.
I turned my eyes again on Rouletabille.
"Ah,--Monsieur Fred!" he said, "when did you begin to use a walking-stick?
I have always seen you walking with your hands in your pockets!" "It is a present," replied the detective.
"Recent ?" insisted Rouletabille.
"No, it was given to me in London." "Ah, yes, I remember--you have just come from London.

May I look at it ?" "Oh!--certainly!" Fred passed the cane to Rouletabille.

It was a large yellow bamboo with a crutch handle and ornamented with a gold ring.

Rouletabille, after examining it minutely, returned it to Larsan, with a bantering expression on his face, saying: "You were given a French cane in London!" "Possibly," said Fred, imperturbably.
"Read the mark there, in tiny letters: Cassette, 6a, Opera." "Cannot English people buy canes in Paris ?" When Rouletabille had seen me into the train, he said: "You'll remember the address ?" "Yes,--Cassette, 6a, Opera.