“The steel burns just as you, perhaps, have seen a watch-spring burn in a jar of oxygen.  Steel, hard or soft, tempered, annealed, chrome, or Harveyized, it all burns just about as fast, and just about as easily under this torch.  And it’s cheap, too.  This attack—­aside from what it costs to the safe—­may amount to a couple of dollars as far as the blow-pipe is concerned—­quite a difference from the thousands of dollars’ loss that would follow an attempt to blow a safe like this one.”

We had nothing to say.  We stood in awe-struck amazement as the torch slowly, inexorably traced a thin line along the edge of the combination.

Minute after minute sped by, as the line burned by the blow-pipe cut around the lock.  It seemed hours, but really it was minutes.  I wondered when he would have cut about the whole lock.  He was cutting clear through and around it, severing it as if with a superhuman knife.

With something more than half his work done, he paused a moment to rest.

“Walter,” he directed, mopping his forehead, for it was real work directing that flaming knife, “get New York on the wire.  See if O’Connor is at his office.  If he has any report, I want to talk to him.”

It was getting late and the service was slackening up.  I had some trouble, especially in getting a good connection, but at last I got headquarters and was overjoyed to hear O’Connor’s bluff, Irish voice boom back at me.

“Hello, Jameson,” he called.  “Where on earth are you?  I’ve been trying to get hold of Kennedy for a couple of hours.  Rockledge?  Well, is Kennedy there?  Put him on, will you?”

I called Craig and, as I did so, my curiosity got the better of me and I sought out an extension of the wire in a den across the hall from the library, where I could listen in on what was said.

“Hello, O’Connor,” answered Craig.  “Anything from Burke yet?”

“Yes,” came back the welcome news.  “I think he has a clue.  We found out from here that she received a long distance message during the afternoon.  Where did Jameson say you were—­Rockledge?—­ that’s the place.  Of course we don’t know what the message was, but anyhow she went out to meet some one right after that.  The time corresponds with what the maid says.”

“Anything else?” asked Craig.  “Have you found any one who saw her?”

“Yes.  I think she went over to your laboratory.  But you were out.”

“Confound it!” interrupted Craig.

“Some one saw a woman there.”

“It wasn’t the maid?”

“No, this was earlier—­in the afternoon.  She left and walked across the campus to the Museum.”

“Oh, by the way, any word of Norton?”

“I’m coming to that.  She inquired for Norton.  The curator has given a good description.  But he was out—­hadn’t been there for some time.  She seemed to be very much upset over something.  She went away.  After that we’ve lost her.”