They passed at length, and at precisely the appointed time Kennedy and I met.  With suppressed excitement, at least on my part, we walked over to Vincenzo’s.  At night this section of the city was indeed a black enigma.  The lights in the shops where olive oil, fruit, and other things were sold, were winking out one by one; here and there strains of music floated out of wine-shops, and little groups lingered on corners conversing in animated sentences.  We passed Albano’s on the other side of the street, being careful not to look at it too closely, for several men were hanging idly about—­pickets, apparently, with some secret code that would instantly have spread far and wide the news of any alarming action.

At the corner we crossed and looked in Vincenzo’s window a moment, casting a furtive glance across the street at the dark empty store where the police must be hiding.  Then we went in and casually sauntered back of the partition.  Luigi was there already.  There were several customers still in the store, however, and therefore we had to sit in silence while Vincenzo quickly finished a prescription and waited on the last one.

At last the doors were locked and the lights lowered, all except those in the windows which were to serve as signals.

“Ten minutes to twelve,” said Kennedy, placing the oblong box on the table.  “Gennaro will be going in soon.  Let us try this machine now and see if it works.  If the wires have been cut since we put them up this morning Gennaro will have to take his chances alone.”

Kennedy reached over and with a light movement of his forefinger touched a switch.

Instantly a babel of voices filled the store, all talking at once, rapidly and loudly.  Here and there we could distinguish a snatch of conversation, a word, a phrase, now and then even a whole sentence above the rest.  There was a clink of glasses.  I could hear the rattle of dice on a bare table, and an oath.  A cork popped.  Somebody scratched a match.

We sat bewildered, looking at Kennedy for an explanation.

“Imagine that you are sitting at a table in Albano’s back room,” was all he said.  “This is what you would be hearing.  This is my ’electric ear’—­in other words the dictograph, used, I am told, by the Secret Service of the United States.  Wait, in a moment you will hear Gennaro come in.  Luigi and Vincenzo, translate what you hear.  My knowledge of Italian is pretty rusty.”

“Can they hear us?” whispered Luigi in an awe-struck whisper.

Craig laughed.  “No, not yet.  But I have only to touch this other switch, and I could produce an effect in that room that would rival the famous writing on Belshazzar’s wall—­only it would be a voice from the wall instead of writing.”

“They seem to be waiting for someone,” said Vincenzo.  “I heard somebody say:  ‘He will be here in a few minutes.  Now get out.’”

The babel of voices seemed to calm down as men withdrew from the room.  Only one or two were left.