"Can't you? It will be getting in advance of the story a bit, but I may as well explain it now as later. I had come to the point of certainty regarding the making of a tunnel--how, you shall hear later--and as a tunnel of 288 feet in length will require shoring up and bracing with balks at intervals if one doesn't want it to become one's grave, timber for that purpose becomes a necessity. Now, as it would have been a pretty risky business to have left a trail by purchasing timber, and a worse one to attempt to smuggle it into the Hurdons' cottage, I had to figure out just where those beauties were going to get it. Old or new, they simply must have it, and the idea of _old_ timber set my thoughts going--opened up, as it were, the possibility of the adjoining house being kept tenantless so that they could quietly demolish it and get the wood from there. So, when I went to lay the fullers' earth about the tower, I determined to have a look inside that other cottage and decide the point. A skeleton key let me in, and one flicker of my torch settled the question. The floors were up, the walls had been broken with a sledge-hammer until the place was fairly littered with mortar and lime from end to end, and every joist and beam that could be removed without bringing the place down had been taken away. I made a rapid inventory, calculated roughly about how much timber it would take to supply what had been removed, reduced that to the requirements of the tunnel, and when you caught me going about that little problem in mental arithmetic, I was trying to discover just how far those chaps must have progressed with the tunnel on the basis of the cubic feet of timber used. "Now, to get back to the beginning. The tunnel idea was really the outcome of speculating with regard to Sir Julius Solinski's possible connection with the matter. That, of course, set me to thinking on the subject of digging for the purpose of getting something out of the earth by secret means and defeating the duke that way; then, when I got to thinking over Captain Paul Sandringham's position in the event of the proposed marriage and the possibility of an heir coming between him and his expectations, and added to that my knowledge of the dishonest character of the man--why, there you are! The tunnel and the reason for it simply evolve themselves by natural means out of such fertile soil as that; and, this much accomplished, it was but a step to the Hurdons and that very delightful garden which was so delightfully kept." "How?"