"Yes, that is ingenious," he said.
He drained off the water, folded back his sleeve, and plunged his arm into the tank. Then he uttered a little cry. He drew up into the light an oblong metal can, like a sandwich-case, with the edges soldered together to make it water-tight. He slipped it into his pocket and turned again to the window. He looked at it again curiously.
"Yes, that is ingenious," he said softly, like a man speaking to himself. Then he led the way back to his office, looking in at the guard-room on the platform to give an order on the way.
The soldered edges of the case were quickly split asunder and a small package of letters written on very thin paper revealed.
"You will let me take these on with me," pleaded Martin. "You shall have them again. But some of them may want a special treatment of which we have the secret."
M. de Cassaud was doubtful about the propriety of such a procedure.
"After all I found them," Martin urged.
"It would be unusual," said M. de Cassaud. "The regulations, you know——"
Martin Hillyard smiled.
"The regulations, for you and me, my friend, are those we make ourselves."