Along one side wall for its whole length was nailed a series of horizontal laths twelve inches apart. What their purpose was he did not know, but he saw that they made a ladder twenty feet wide, by which a man could work his way from the passage to the end wall and reach the water at any height of the tide.

Above this ladder was an object which at first puzzled the inspector, then as he realized its object, it became highly illuminating. On a couple of brackets secured to the wall lay a pipe of thin steel covered with thick black baize, and some sixteen feet long by an inch in diameter. Through it ran the light copper pipe which was connected at its other end to the pump. At the end of the passage this pipe had several joints like those of a gas bracket, and was folded on itself concertina-wise.

The inspector stepped on to the ladder and worked his way across it to the other end of the steel pipe, close by the end wall. The copper pipe protruded and ended in a filling like the half of a union. As Willis gazed he suddenly grasped its significance.

The side of the Girondin, he thought, would lie not more than ten feet from where he was standing. If at night someone from within the cellar were to push the end of the steel tube out through one of the spaces between the horizontal timbers of the end wall, it could be inserted into a porthole, supposing one were just opposite. The concertina joints would make it flexible and allow it to extend, and the baize covering would prevent its being heard should it inadvertently strike the side of the ship. The union on the copper tube could then be fixed to some receptacle on board, the brandy being pumped from the ship to the tun.

And no outsider could possibly be any the wiser! Given a dark night and careful operators, the whole thing would be carried out invisibly and in absolute silence.

Now Willis saw the object of the peculiar construction of the front of the wharf. It was necessary to have two lines of piles, so that the deck between might overshadow and screen from view the openings between the horizontal beams at the front of the cellar. He stood marvelling at the ingenuity of the plan. No wonder Hilliard and Merriman had been baffled.

But if he were to finish his investigations, he must no longer delay. He worked back across the side of the cellar, regained the passage, and returned to the pump-room. Then turning into the other passage, he began to walk as quickly as possible along it.

The tunnel was barely four feet high by three wide, and he found progress very tiring. After a slight curve at the mouth it ran straight and almost dead level. Its construction was the same as that of the cellar, longitudinal timber lining supported behind verticals and lintels spaced about six feet apart. When he had gone about two hundred yards it curved sharply to the left, ran heavily timbered for some thirty yards in the new direction, and then swung round to the right again.

“I suppose the railway crosses here,” Willis thought, as he passed painfully round the bends.

The sweat stood in drops on his forehead when he reached the end, and he breathed a sigh of relief as he realized he could once more stand upright and stretch his cramped back. He found himself in another cellar, this time about six feet by twelve. The tramway ran along it, stopping at the end wall. The place was otherwise empty, save for a wooden grating or tun-dish with a hinged lid which was fixed between the rails near the entrance. The telephone wires, which had followed the tunnel all the way, here vanished into the roof.