McCausland turned to Dr. Perkins. "Will you explain to our young but over-enthusiastic friend about that?"
Dr. Perkins shook his head. The frown still persisted. "Not if it's a true isotope. That would be the same thing as transmuting elements. But I still confess I do not entirely understand."
McCausland took up the word swiftly. "Meanwhile, since it is certain that the metal used by these Plutonians will not do for our purpose, I think it important that we at least look into the composition of their civilization to some extent," he remarked. "I propose to investigate them with Professor Reuter's co-operation. Mister Longworth, you will take charge of the ship guard."
Paulette spoke up suddenly. "Captain McCausland, I think it is important that I go with you on making this contact with the Plutonians. Certainly everyone on the three planets will want to know about them."
The captain's mouth writhed a moment, and Adam noticed the glance he shot at Professor Reuter, but his voice was smooth. "To be sure, Miss de Vries. I think, then, this is all that comes before the present meeting. Dismiss."
The space in front of the metal wall that shut off the Plutonian domain had been cleared. As Paulette, accompanied by Professor Reuter, McCausland, and Bjornsen of the engine-room staff, reached the bottom of the dig and stepped over to it, they noted that although the wall still showed part of the jagged break, a door had been fitted to fill most of the gap.
The four stepped over to it, and McCausland tapped at the door. There was no answer at first, then from the other side there came an answering tapping—one tap, then two, then three, as though for a signal. McCausland answered in the same fashion, and after a moment the door slid back, revealing one of the strange ape men of Pluto. He saluted in a strange copy of the movement Adam had made at the time of their first contact, and McCausland, returning the salute, stepped through the door, and producing a piece of paper from his pocket began to make sketches, while the dwarf watched with interest, his face working rapidly to indicate comprehension.
After a moment the captain beckoned to Reuter and both stepped down into the Plutonian room, leaving Paulette and Bjornsen on the heap of rubble at the base of the digging. The girl looked round, then in a low voice, said to the engineer:
"Will you do me a favor?"