Seaton opened the door. As he did so, a number of the smaller beings dived headlong into the water, and a submarine rose quietly to the surface less than fifty feet away with a peculiar tubular weapon and a huge ray-generator trained upon the _Skylark_. Seaton stood motionless, his right hand raised in the universal sign of peace, his left holding at his hip an automatic pistol charged with X-plosive shells--while Crane, at the controls, had the Fenachrone super-generator in line, and his hand lay upon the switch, whose closing would volatilize the submarine and cut an incandescent path of destruction through the city lengthwise. * * * * * After a moment of inaction, a hatch opened, a man stepped out upon the deck of the submarine, and the two tried to converse, but with no success. Seaton then brought out the mechanical educator, held it up for the other's inspection, and waved an invitation to come aboard. Instantly the other dived, and came to the surface immediately below Seaton, who assisted him into the _Skylark_. Tall and heavy as Seaton was, the stranger was half a head taller and almost twice as heavy. His thick skin was of the characteristic Osnomian green and his eyes were the usual black, but he had no hair whatever. His shoulders, though broad and enormously strong, were very sloping, and his powerful arms were little more than half as long as would have been expected had they belonged to a human being of his size. The hands and feet were very large and very broad, and the fingers and toes were heavily webbed. His high domed forehead appeared even higher because of the total lack of hair, otherwise his features were regular and well-proportioned. He carried himself easily and gracefully, and yet with the dignity of one accustomed to command as he stepped into the control room and saluted gravely the three other Earth-beings. He glanced quickly around the room, and showed unmistakable pleasure as he saw the power-plant of the cruiser of space. Languages were soon exchanged and the stranger spoke, in a bass voice vastly deeper than Seaton's own. "In the name of our city and planet--I may say in the name of our solar system, for you are very evidently from one other than our green system--I greet you. I would offer you refreshment, as is our custom, but I fear that your chemistry is but ill adapted to our customary fare. If there be aught in which we can be of assistance to you, our resources are at your disposal--but before you leave us, I shall wish to ask from you a great gift." "Sir, we thank you. We are in search of knowledge concerning forces which we cannot as yet control. From the power systems you employ, and from what I have learned of the composition of your suns and planets, I assume you have none of the metal of power, and it is a quantity of that element that is your greatest need?"