'At what time did you reach the Pont de Neuilly?'
'I do not know, sir; I was compelled to drive rather fast, but the distance is seven to eight kilometres.'
'You would do it under the hour?'
'But certainly, under the hour.'
'Then you must have reached Neuilly bridge about four o'clock?'
'It is very likely, sir.'
The plan of the tall American was now perfectly clear to me, and it comprised nothing that was contrary to law. He had evidently placed his luggage on board the steam launch in the morning. The handbag had contained various materials which would enable him to disguise himself, and this bag he had probably left in some shop down the side street, or else someone was waiting with it for him. The giving of the treasure to another man was not so risky as it had at first appeared, because he instantly followed that man, who was probably his confidential servant. Despite the windings of the river there was ample time for the launch to reach Havre before the American steamer sailed on Saturday morning. I surmised it was his intention to come alongside the steamer before she left her berth in Havre harbour, and thus transfer himself and his belongings unperceived by anyone on watch at the land side of the liner.
All this, of course, was perfectly justifiable, and seemed, in truth, merely a well-laid scheme for escaping observation. His only danger of being tracked was when he got into the cab. Once away from the neighbourhood of the Boulevard des Italiens he was reasonably sure to evade pursuit, and the five minutes which his friend with the pistols had won for him afforded just the time he needed to get so far as the Place Madeleine, and after that everything was easy. Yet, if it had not been for those five minutes secured by coercion, I should not have found the slightest excuse for arresting him. But he was accessory after the act in that piece of illegality—in fact, it was absolutely certain that he had been accessory before the act, and guilty of conspiracy with the man who had presented firearms to the auctioneer's audience, and who had interfered with an officer in the discharge of his duty by threatening me and my men. So I was now legally in the right if I arrested every person on board that steam launch.
With a map of the river before me I proceeded to make some calculations. It was now nearly ten o'clock at night. The launch had had six hours in which to travel at its utmost speed. It was doubtful if so small a vessel could make ten miles an hour, even with the current in its favour, which is rather sluggish because of the locks and the level country. Sixty miles would place her beyond Meulan, which is fifty-eight miles from the Pont Royal, and, of course, a lesser distance from the Pont de Neuilly. But the navigation of the river is difficult at all times, and almost impossible after dark. There were chances of the boat running aground, and then there was the inevitable delay at the locks. So I estimated that the launch could not yet have reached Meulan, which was less than twenty-five miles from Paris by rail. Looking up the timetable I saw there were still two trains to Meulan, the next at 10.25, which reached Meulan at 11.40. I therefore had time to reach St. Lazare station, and accomplish some telegraphing before the train left.