"Got the old spirit, all right," he said with twinkling eyes. "I suppose it came from that expedition in Brazil. Every explorer gets it sooner or later." "That's right," agreed Mr. Lewis, Joe's father. "They say the main characteristic of a true explorer is his ability to sense the thrill of adventure." "Then we're real explorers. Isn't that right, Dad?" grinned Bob. "'We'?" asked Mr. Holton, trying to appear serious. "Where do you get that 'we' stuff? You and Joe have only bothered us on one expedition. We men have faced the scorching sun scores of times, and should by now have caught the true meaning of it all. But you boys----" "Wait a minute," cut in Bob, determined not to be beaten so easily. "Where would you have been if it hadn't been for Joe and me? It was our ingenuity that brought about the success of the expedition." "Well, I must say I hadn't thought of that before," laughed Mr. Holton. "It's true, all right." Bob stoutly defended himself and his chum. "If you say the word I'll prove it." Mr. Holton smiled. He took a great delight in arguing in a friendly manner with his son, although at times he was forced to admit defeat. This time he was satisfied to drop the matter and turn his eyes to the western sky, where the sun, a great ball of red fire, was sliding into the bluish waters of the Mediterranean. Gradually the ball faded from view, leaving a soft blue sky, which a moment later became streaked with long gold streamers. At last these became molded into one great mass of color and light, crossed and dotted with every hue of the rainbow. Slowly the spectacle faded from view, and the sky became a warm blue, out of which came countless glittering stars. It was a wonderful sight, and although the adventurers had witnessed it several times before, they never seemed to tire of it. Bob and Joe especially were deeply stirred. "Now that we've seen our last sunset on this voyage, suppose we get our belongings together," said Mr. Holton, getting up from his chair. "It won't be long until we reach Algiers." "And if what we've heard is true, it's a wonderful city," added Mr. Lewis. "Has the most unusual blend of things Arab and European on the globe. Monuments, mosques, palaces, everything and more that characterizes the spirit of North Africa." He arose and led the way up the deck to the cabin, where already people were gathering to await the first sight of land. Among the passengers were brightly garbed Egyptians, Algerians, Arabs, and many others with quaint and picturesque costumes. Everyone was in a gay mood, laughing and talking merrily. That is, all but two tall Arabs, whose quiet gaze was fixed on Bob, Joe, and the others of the American expedition. That the men intended mischief was sensed by the boys, although their elders had caught no element of danger.