What was the energy source? No one knew, but the best suspect was the heat of the planet's core.
There was speculation that some kind of metal shield lay between the crust of the earth and the deeper layers. That there was no volcanic activity or earthquakes tended to strengthen this hypothesis.
Since there were no vast ice or water masses making a temperature differential comparable to that of Earth, the wind conditions could have been different. But, so far, the pattern seemed to be Terrestrial.
Firebrass decided to take the ship down to 3600 meters altitude, a little over 12,000feet. Perhaps the wind there might be weaker. The mountain tops were only 610 meters or about 2000 feet below the vessel, and the effect of the up- and downdrafts were strong at this time of the day. But the ability to change the angle of the propellers swiftly compensated somewhat for this roller-coaster motion. The ground speed increased.
Before 15:00, Firebrass ordered that the vessel be taken up above the rainclouds. He brought it back down at 16:00, and the Parseval rode majestically above the valleys. As the sun descended, both the horizontal and vertical winds would weaken, and the ship could plow through the air more evenly.
When night came, the hydrogen in the cells would cool, and the vessel would have to lift its nose even higher to give it more dynamic lift to compensate for the loss of buoyancy.
The pressurized control room was wanned by electric heaters. Its occupants were, however, in heavy cloths. Firebrass and Piscator were smoking cigars; most of the others, cigarettes. The fans sucked the smoke away but not quickly enough to remove the cigar odor which Jill so detested.
Hydrogen-emission detectors placed by the gas cells would transmit a warning if there were any leaks. Nevertheless, smoking was permitted only in five areas: the control gondola or bridge, a room halfway along the vessel's axis, the auxiliary control room in the lower tail fin, and rooms attached to the quarters of the crew fore and aft.
Barry Thorn, first officer of the tail section, reported some magnetic readings. According to this, the North Pole of The River-world coincided with the north magnetic pole. The magnetic force itself was much weaker than that of Earth's, so slight, in fact, that it would have been undetectable without the use of instruments known only in the late 1970's.
"Which means," Firebrass said, laughing, "that there are three poles on one spot. The North Pole, the magnetic pole, and the tower. Now, if only one of our crew was a Pole, we could have four on the same place."
Radio reception was excellent today. The ship was high above the mountains, and the transceiver of the Mark Twain was carried by a balloon towed by the boat.
Aukuso said, "You can talk now, sir."
Firebrass sat down by the Samoan's side and said, "Firebrass here, Sam. We just got word from Greystock. He's on the way, heading northeastward, ready to alter course the moment he gets wind of the location of the Rex."
"In some ways I hope you don't find Rotten John," Sam said. "I'd like to catch up with him and so have the pleasure of sinking him myself. That's not a very practical attitude, though it's mighty satisfying. I'm not a vindictive man, Milt, but that hyena would make St. Francis himself long to kick him off a cliff."
"The Minerva's carrying four forty-six-kilogram bombs and six rockets with nine-kilogram warheads,'' Firebrass said. "If only two of the bombs make a direct hit, they could sink the boat."
"Even so, that royal thief might get away safe and sound to shore," Clemens said. "He has all the good luck of the wicked. How would I ever find him then? No, I want to see his body. Or if he's taken alive, I want to wring his neck myself."
De Bergerac spoke softly to Jill. "Clemens talks big for a man who's appalled by violence. It's easy to do as long as the enemy's sixty thousand kilometers away."
Firebrass laughed and said, "Well, if you can't twist his head off, Sam, Joe's the man to do the job."
An unhumanly deep voice rumbled, "No, I'll tear off hith armth and legth. Then Tham can turn hith head around tho he can thee vhere he'th been. He von't like where he'th going."
"Tear off an ear for me," Firebrass said. "Old John almost hit me when he shot at me."
Jill presumed that he was referring to the fight aboard the Not For Hire when John had seized it.
Firebrass said, "According to calculations, the Rex should be in the area we'll be over in about an hour. You should be in the same area but about one hundred forty kilometers to the west of the Rex. Of course, we could be way off. For all we know, the Rex may not be traveling as fast as it could, or King John could've decided to dock for repairs or a very long shore leave."
An hour's conversation followed. Clemens talked to some of the crew, mostly those he had known before he'd left Paiolando. She noticed that he did not ask to speak to de Bergerac.
Just as Sam was about to sign off, the radar operator reported that the Rex Grandissimus was on the scope.
45
Staying at 452 meters altitude, the Parseval circled the boat. From that height it looked like a toy, but photographs, quickly enlarged, showed that it was indeed King John's vessel. It was magnificent. Jill thought that it would be a shame to destroy such a beautiful craft, but she did not say so. Firebrass and de Bergerac felt very strongly about the man who had hijacked their fabulous River-boat.
Aukuso transmitted the location to Greystock, who said that the Minerva should reach the Rex the following day. He also checked the location of the Mark Twain.
"I'd like to fly over her so that Sam can get a good look at the ship that's going to sink the Rex," Greystock said.
"It won't take you out of your way to do that," Firebrass said. "And it'll give Sam a big thrill."
After he had quit talking to Clemens, Firebrass said, "I really think Greystock's on a suicide mission. The Rex is loaded with rockets, and it carries two planes armed with rockets and machine guns. It all depends on whether or not Greystock can catch the Rex by surprise. Not much chance of that if John's radar detects the Minerva. Of course, it might be off. Why should it be on? The sonar is good enough for daytime navigation."
"Yes," Piscator said. "But the people on the Rex must have seen us. They'll be wondering about us, though they won't know who we are, and they might start using the radar because they'll be suspicious."
"I think so, too," Jill said. "They can figure out easily enough that only Parolando could build a dirigible.''
"Well, we'll see. Maybe. By the time the Minerva gets to the Rex, we'll be behind the polar mountains. I don't think we can expect good radio reception there. We'll have to wait until we come back over them."
Firebrass looked thoughtful, as if he were wondering if the Parseval would return.