I awoke to find Kennedy dozing in a chair, partly dressed, but just as fresh as I was after my sleep.  I think he had been dreaming out his course of action.  At any rate, breakfast was a mere incident m his scheme, and we were over at the tunnel works when the night shift were going off.

Kennedy carried with him a moderate-sized box of the contents of which he seemed very careful.  Paddy was waiting for us, and after a hasty whispered conversation, Craig stowed the box away behind the switchboard of the telephone central, after attaching it to the various wires.  Paddy stood guard while this was going on so that no one would know about it, not even the telephone girl, whom he sent off on an errand.

Our first inspection was of that part of the works which was above ground.  Paddy, who conducted us, introduced us first to the engineer in charge of this part of the work, a man named Shelton, who had knocked about the world a great deal, but had acquired a taciturnity that was Sphinx-like.  If it had not been for Paddy, I fear we should have seen very little, for Shelton was not only secretive, but his explanations were such that even the editor of a technical journal would have had to blue pencil them considerably.  However, we gained a pretty good idea of the tunnel works above ground—­at least Kennedy did.  He seemed very much interested in how the air was conveyed below ground, the tank for storing compressed air for emergencies, and other features.  It quite won Paddy, although Shelton seemed to resent his interest even more than he despised my ignorance.

Next Paddy conducted us to the dressing-rooms.  There we put on old clothes and oilskins, and the tunnel doctor examined us and extracted a written statement that we went down at our own risk and released the company from all liability—­much to the disgust of Paddy.

“We’re ready now, Mr. Capps,” called Paddy, opening an office door on the way out.

“Very well, Flanagan,” answered Capps, barely nodding to us.  We heard him telephone some one, but could not catch the message, and in a minute he joined us.  By this time I had formed the opinion, which I have since found to be correct, that tunnel men are not as a rule loquacious.

It was a new kind of thrill to me to go under the “air,” as the men called it.  With an instinctive last look at the skyline of New York and the waves playing in the glad sunlight, we entered a rude construction elevator and dropped from the surface to the bottom of a deep shaft.  It was like going down into a mine.  There was the air-lock, studded with bolts, and looking just like a huge boiler, turned horizontally.

The heavy iron door swung shut with a bang as Paddy and Capps, followed by Kennedy and myself, crept into the air-lock.  Paddy turned on a valve, and compressed air from the tunnel began to rush in with a hiss as of escaping steam.  Pound after pound to the square inch the pressure slowly rose until I felt sure the drums of my ears would burst.  Then the hissing noise began to dwindle down to a wheeze, and then it stopped all of a sudden.  That meant that the air-pressure in the lock was the same as that in the tunnel.  Paddy pushed open the door in the other end of the lock from that by which we had entered.