"Not in daylight. I want to find some other way out for that. You see," explained Dave, "this is just an ideal spot as a rendezvous. I want to get over to the city tomorrow, though, to attend to some important business." "How are you going to get there?" "Why, I'll have to trust to my swimming skill, I guess," replied Dave. "Um-m," observed Hiram thoughtfully, and, if the young aviator had been more watchful, he would have noticed that for the rest of the evening his willing assistant seemed to have something on his mind. CHAPTER XIX THE SEARCHLIGHT "Hallo! Hallo!" Dave made the echoes ring with the loud call as he moved up and down and across the queer basin, or cairn, where they had landed in the Monarch II the night previous. He had awakened just at daylight to find Hiram Dobbs mysteriously missing. Dave was not worried at the first, but as he looked around and then explored the immediate neighborhood, he began to get mystified, if not alarmed. Neither did his vigorous shouting bring any response. Dave came back to the camp spot to make a new discovery that puzzled him. On the ground near where they had slept were Hiram's coat, vest, shoes and cap. "Why, I can't understand this at all," mused the young aviator. "Hiram couldn't have done much in the way of climbing up, he appears to be nowhere within hail, and he is not given to play tricks." Dave did not wait to eat anything. He was really concerned about his comrade. He got a long tree branch, stripped it, and went along the side of the cairn, poking in and out among the dense dumps of shrubbery. "Hello," he exclaimed suddenly, as disturbing some vines he saw an opening, and not twenty feet away a natural rocky tunnel, "daylight, and the waves of the lake. I think I understand now." Dave penetrated the passage. As he came out at the other end, he found he faced a rock-strewn stretch of sand. The waves of the lake lapped this. In the distance he could make out Anseton, and nearer still, about a mile distant, the main shore. The shore he was on terminated in a ridge of rocks that ran far out into the water. Dave wondered if the exploring spirit had moved Hiram to attempt an entire circle about the island. "He went away in swimming trim," thought Dave, "so that may be so. I'll go out on that ledge of rocks and explore a little myself." "Hello, Dave Dashaway!" sang out an exultant voice, just as Dave was about to remove his shoes. Around the ledge of rock came a light skiff. The oarsman was Dave's missing comrade. He drove the boat upon the sandy beach and leaped out with a gay laugh. "Why, Hiram," exclaimed the young aviator in marked surprise. "It's me," chuckled Hiram. "Stole a march on you. Nearly dry," he added, shaking his clinging garments. "And oh! what a swim." "You have been to the mainland?" questioned Dave.