As he spoke Juve tossed his hat aside and, looking at a rather high kind of little table, proceeded to remove from it a grey cloth which protected it from dust, and drew it into the middle of the room. This article was composed of a metal body screwed on to a strong tripod, with a lower tray that moved backwards and forwards, and two lateral buttresses with a steel cross-piece firmly bolted on to them above. Upon this framework were two dynamometers worked by an ingenious piece of mechanism. Juve looked at Charles Rambert and explained.
"This is Dr. Bertillon's effraction dynamometer. I am going to make use of it to find out at once whether you are or are not deserving of some little interest. I don't want to tell you more just at present." Juve slipped into a specially prepared notch a thin strip of wood, which he had selected with particular care from one of the heaps of material arranged along the wall. From a chest he took a tool which Charles Rambert, who had had some intimate experience of late with the light-fingered community, immediately recognised as a jemmy. "Take hold of that," said Juve, and as Charles took it in his hand he added: "Now put the jemmy into this groove, and press with all your force. If you can move that needle to a point which I know, and which it is difficult but not impossible to reach, you may congratulate yourself on being in luck."
Stimulated by this encouragement from the detective, Charles Rambert exerted all his force upon the lever, only afraid that he might not be strong enough. Juve stopped him very soon.
"That's all right," he said, and substituting a strip of sheet-iron for the strip of wood, he handed another tool to the lad. "Now try again."
A few seconds later Juve took a magnifying lens, and closely examined both the strip of metal and the strip of wood. He gave a little satisfied click with his tongue, and seemed to be very pleased.
"Charles Rambert," he remarked, "I think we are going to do a very good morning's work. Dr. Bertillon's new apparatus is an uncommonly useful invention."
The detective might have gone on with his congratulatory monologue had not an attendant come into the room at that moment.
"Ah, there you are, M. Juve: I have been looking for you everywhere. There is someone asking for you who says he knows you will receive him. I told him this was not the proper time, but he was so insistent that I promised to bring you his card. Besides, he says you have given him an appointment."
Juve took the card and glanced at it.
"That's all right," he said. "Take the gentleman into the parlour and tell him I will be with him in a minute." The attendant went out and Juve looked at Charles Rambert with a smile. "You are played out," he said; "before we do anything else common humanity requires that you should get some rest. Come, follow me; I will take you to a room where you can throw yourself on a sofa and get a sleep for a good hour at least while I go and see this visitor." He led the lad into a small waiting-room, and as Charles Rambert obediently stretched himself upon the sofa, Juve looked at the pale and nervous and completely silent boy, and said with even greater gentleness: "There, go to sleep; sleep quietly, and presently —— "
Juve left the room, and called a man to whom he gave an order in a low tone.
"Stay with that gentleman, please. He is a friend of mine, but a friend, you understand, who must not leave this place. I am going to see some one, but I will come up again presently," and Juve hurried downstairs to the parlour.
The visitor rose as the door opened, and Juve made a formal bow.
"M. Gervais Aventin?" he said.
"M. Gervais Aventin," that gentleman replied. "And you are Detective-Inspector Juve?"
"I am, sir," the detective answered, and pointing his visitor to a chair he took a seat himself at a small table littered with official documents.
"Sir," Juve began, "I ventured to send you that pressing invitation to come to Paris to-day, because from enquiries I had made about you, I was sure that you were a man with a sense of duty, who would not resent being put to inconvenience when it was a question of co-operating in a work of justice and of truth."
The visitor, a man of perhaps thirty, of somewhat fashionable appearance and careful though quiet dress, manifested much surprise.
"Enquiries about me, sir? And pray, why? I must confess that I was very much astonished when I received your letter informing me that the famous Detective-Inspector Juve wished to see me, and at first I suspected some practical joke. On consideration I decided to obey your summons without further pressing, but I did not imagine that you would have made any enquiries about me. How do you know me, may I ask?"
Juve smiled.
"Is it the fact," he enquired, instead of replying directly, for like the good detective that he was, intensely keen on his work, he enjoyed mystifying people with whom he conversed, "is it the fact that your name is Gervais Aventin? A civil engineer? The possessor of considerable private means? About to be married? And that lately you made a short journey to Limoges?"
The young man nodded and smiled.
"Your information is perfectly correct in every particular. But I do not yet understand what crime of mine can have subjected me to these enquiries on your part."
Juve smiled again.
"I wondered, sir, why you vouchsafed no answer to the local enquiries which have been made at my instance, to the advertisements which I have had inserted in the papers, in which I discreetly made it known that the police wanted to get into communication with all the passengers who travelled first class, in the slow train from Paris to Luchon, on the night of the 23rd of December last."
This time the young man looked anxious.
"Great Scott!" he exclaimed, "are you in the employment of my future father-in-law?"
Juve burst into a roar of laughter.
"First acknowledge that you did travel by that train on that night: that you got into it at Vierzon, where you live and where you are going to be married; and that you were going to Limoges to see a lady — and that you did not want your fiancée's family to know anything about it."
Gervais Aventin pulled himself together.
"I had no idea that the official police undertook espionage of that sort," he said rather drily. "But it is true, sir, that I went to Limoges — my last post before I was appointed to Vierzon — to take a final farewell to a lady. But since you are so accurately informed about all this, since you even know what train I went by, a train I deliberately chose because in little places like Vierzon so much notice is taken of people who travel by the express, you must also know —— "
Juve checked him with a wave of the hand.
"A truce to jesting," he said; "excuse me, sir, I was only amusing myself by observing once more how quickly decent people, who have a little peccadillo on their conscience, are disturbed when they think they have been found out. Your love affairs do not matter to me, sir; I don't want to know if you have a lady friend, or not. The information I want from you is of a very different nature. Tell me simply this: in what circumstances did you make that journey? What carriage did you get into? Who travelled with you in that carriage? I am asking you because, sir, I have every reason to believe that you travelled that night with a murderer who committed a crime of particular atrocity, and I think you may be able to give me some interesting information."
The young man, who had been looking grave, smiled once more.
"I would rather have that than an enquiry into my defunct love affairs. Well, sir, I got into the train at Vierzon, into a first-class carriage —— "
"What kind of carriage?"
"One of the old-fashioned corridor carriages; that is to say, not a corridor communicating with the other carriages, but a single carriage with four compartments, two in the middle opening on to the corridor, and two at the ends communicating with the corridor by a small door."
"I