attempt upon your lock, an invisible plate will open of itself and vomit forth a pretty copper bullet the weight of a mark — which will knock down the intruder, and not with a loud report. What do you think of it?”

“I think it very ingenuous,” cried D’Artagnan; “the little copper bullet pleases me mightily. So now, sir mechanic, the terms?”

“A fortnight for the execution, and fifteen hundred livres payable on delivery,” replied the artisan.

D’Artagnan’s brow darkened. A fortnight was delay enough to allow the thieves of London time to remove all occasion for the strong box. As to the fifteen hundred livres — that would be paying too dear for what a little vigilance would procure him for nothing.