"Ah! The cause of Sixty's work is becoming clearer and clearer. He knew I was a friend of yours, that the government had asked me to watch him, and that you had had a chance to secure some important information from the telegram. It was enough to make a man like Sixty try something desperate!"
"You were watching him?" queried Matt, "and for the government?"
"Yes. Sixty has been a trader in the South Seas, but lately he has caused the government to suspect him of an attempt to smuggle arms and ammunition to Central America to help out some revolutionists there. His brig, the Dolphin, cleared from New Orleans a few weeks ago, having dropped in at that port from across the ocean, and has since mysteriously vanished. It has been something like a week since Sixty showed up in New Orleans again. The government had communicated with me before I came to the South, asking me to locate the Dolphin, follow her and see what she was up to. If I couldn't find the brig I was to follow Sixty. That was the business on which I wanted your aid, but I couldn't tell you anything about it until the time came for us to act. You see, I didn't want Sixty to think that he was being watched. When Clackett, who was shadowing Sixty, brought me word that he had just seen him leaving New Orleans on the Santa Maria, I immediately made preparations to follow the steamer; and I was more anxious than ever to trail her when Clackett reported that you and your friends, as well as Sixty, were on the boat. I knew, at once, that there was some crooked work afoot.
"We gained on the steamer in the river, and came within sight of her two or three hours after she had reached the gulf. We submerged the Grampus until the periscope ball was just awash and trailed along in her wake. On the periscope table I saw some one drop overboard, and we immediately emptied our ballast tanks and came to the surface. I was surprised enough when I found that it was you who was in the water, Matt. We were too far away to see Sixty throw you over the rail. The truth of the matter is, Sixty is afraid of you—afraid you would tell me what was contained in that telegram. The bearings set forth by that latitude and longitude must have been mighty important!"
"Your work for the government," commented Matt, "in spite of the way you guarded it, must have become known to Sixty."
"Yes; but he did not learn it through me. Some one in Washington must have kept him informed."
"The girl also seemed to have a pretty good knowledge of the fact that I was going to help you."
"Sixty may have inferred that, and if the girl talked guardedly with you she might still further have developed the point."
"That's exactly what she did!" exclaimed Matt, with sudden divination. "I can see now that she was playing a part all the time. I don't think she liked the work, but that she was forced to do it by her father."
"Sixty's a rough old webfoot, and when his unscrupulous mind counsels a course he's not at all particular as to the ways and means by which he keeps to it."