"Our visit has been most happily timed.

There is a letter in the box." "Well," I said, "we can't get it out; and if we could, it would be hardly justifiable." "I don't know," he replied, "that I am prepared to assent off-hand to either of those propositions; but I would rather not tamper with another person's letter, even if that person should happen to be a murderer.
Perhaps we can get the information we want from the outside of the envelope." He produced from his pocket a little electric lamp fitted with a bull's-eye, and, pressing the button, threw a beam of light in through the grille.

The letter was lying on the bottom of the box face upwards, so that the address could easily be read.
"Herrn Dr.H.Weiss," Thorndyke read aloud.

"German stamp, postmark apparently Darmstadt.

You notice that the 'Herrn Dr.' is printed and the rest written.