He looked about the room quickly.  Beside a window that opened out over a house several stories below stood a sectional bookcase.  Into this bookcase, back of the books, in the shadow, he shoved the little box, to which he had already attached a spool of twisted wires.  Then he opened the window and dropped the spool out, letting it unwind of its own weight until it fell on the roof far below.  He shut the window and rejoined me without a word.

A moment later she returned with the dainty note which she had written.  “Shall I send it by a messenger?” she asked.

“Yes, please,” answered Kennedy, rising.  As he moved a step to the door he held out his hand to her.  “Senorita Mendoza,” he said simply, in a tone that meant more than words, “you are a wonderful woman.”

She took his hand without a word, and a moment later we were whisked down in the elevator.

“I must get on that roof on some pretext,” remarked Kennedy, as we reached the street and he got his bearings.  “Let me see, that house which backs up to the apartment is around the corner.  Have the man drive us around there.”

We located the house and mounted the steps.  On the wall beside the brownstone door was pasted a little slip of paper, “Furnished Rooms.”

“Splendid!” exclaimed Kennedy, as he read it.  “Dismiss the taxi and meet me inside with the other package.”

By the time I had paid the man and come up the steps again Kennedy had made a dicker with the landlady for a double room on the third floor for both of us, and, by payment of a week’s rent, we were to have immediate possession.

“Our baggage will follow to-day,” he explained, as we mounted the stairs to the room.

I thought the landlady would never get through expatiating upon what a select place she ran, and thus leave us alone in our room, but at last even her flood of words was stilled by demands from a servant downstairs who must be instructed if the selectness of the establishment were to be maintained.

No sooner were we alone than Kennedy tiptoed into the hall and made sure that we were not watched.  It was then the work of only a few seconds to mount a ladder to a scuttle, unhook it, and gain the roof.

There, dangling down from the dizzy height above, swayed the twisted wire.  He seized it, unrolled it some more, and sent me downstairs to catch it, as he swung it over the edge of the roof to one of our own windows.  Then he rejoined me.

The other package, which had been heavier, consisted of another of those mysterious boxes, as well as several dry cells.  Quickly he attached the wires to the box, placing the dry cells in the circuit.  Then he began adjusting the mechanism of the box.  So far I had only a vague idea of just what he had in mind, but gradually it began to dawn on me.

It was perhaps half an hour, perhaps longer, after we had left the Senorita, before, sure that everything was all right with his line and the batteries which he had brought, Kennedy turned a little lever that moved in a semicircle, touching one after another of a series of buttons on the face of the cedar box, meanwhile holding a little black disc from the back of the box to his ear as he adjusted the thing.