"Well, I wonder how that moves?" said Jack. "They're not rowing, they have no sail, and I can't see any engine."
"Maybe thought power moves the boat, too," suggested Mark.
"It certainly seems so," rejoined Mr. Henderson.
The travelers found themselves stopping, and their leader, turning, said something to the persons in the boat. There was a brief conversation in the strange language, and the adventurers found themselves moving into the craft, which stopped close to the bank of the canal. When they were seated the boat started off again, and though Jack and Mark, as well as the two men, looked closely to ascertain what was the motive power, they could not discover it.
"Unless it's in that small box," said Jack, pointing to one made of some shining metal, in the stern of the boat.
"Perhaps it is," assented Mr. Roumann. Then he made some motions to the guide, asking whether or not the substance in the box contained the motive power.
The man with the squared triangle on his head seemed to hesitate a moment, and then, with a motion to the Martian in charge of the boat, he said something, and the latter opened the box. Mr. Roumann looked eagerly into it, as did the others, and the German uttered a cry of surprise.
And well he might, for all the box contained was a lump of what seemed to be red clay. There were no wheels, no machinery of any kind, and there appeared to be no propeller on the boat with which the box was connected. Nevertheless, the craft continued to move along swiftly, and the Martian had indicated that the object in the box made it go.
"The red substance!" exclaimed Mr. Roumann in a low voice. "I wonder if this can be what I seek?"
Once more he looked at the crimson mass in the metal box. He reached forward his finger as if to touch it, but the chief Martian, with a warning cry, suddenly dosed down the lid.