"We have the laboratory——" Trainor began.
"But we lack one essential thing. We must have a small amount of cerium, one of the rare earth metals. For the electrode, you know, inside the vitalium grid in our new vacuum tube. And there is not a gram of cerium in all our supplies."
"We can go back to the Earth——" said Trainor.
"That will mean forty days gone, before we could come back—more than forty, because we would have to stop at the City of Space to refit. And all the perils of the meteorites again. I am sure that in less than forty days the Martians will be putting the machine in that enormous blue globe to its dreadful use."
"Then we must land on Mars and find the metal!" said Captain Brand, who had been listening by the door.
"Exactly," said the Prince. "You will pick out a spot that looks deserted, at a great distance from the blue globe. Somewhere in the mountains, as far back as possible from the canals. Land there just after midnight. We will have mining and prospecting equipment ready to go to work when day comes. Almost any sort of ore ought to yield the small quantity of cerium we need."
"Very good, sir," said Brand.
A few hours later the Red Rover was sweeping around Mars, on a long curve, many thousands of miles from the surface of the red planet.
"We'll pick out the spot to land while the sun is shining on it," Captain Brand told Bill. "Then we can keep over it, as it sweeps around into the shadow, timing ourselves to land just after midnight."