The twins blinked at it. In the upper left-hand corner of the chart they spotted the names of subjects they had studied; the rest of the array was unknown territory; in most cases they did not even recognise the names of the subjects. In the ordinary engineering forms of the calculus they actually were adept; they had not been boasting. They knew enough of vector analysis to find their way around unassisted in electrical engineering and electronics; they knew classical geometry and trigonometry well enough for the astrogating of a space ship, and they had had enough of non-Euclidean geometry, tensor calculus, statistical mechanics, and quantum theory to get along with an atomic power plant
But it had never occurred to them that they had not yet really penetrated the enormous and magnificent field of mathematics.
‘Dad’ asked Pollux in a small voice, ‘what’s a “hyperideal”?’
‘Time you found out.’
Castor looked quickly at his father. ‘How many of these things have you studied, Dad?’
‘Not enough. Not nearly enough. But my sons should know more than I do.’
It was agreed that the twins would study mathematics intensively the entire time the family was in space, and not simply under the casual supervision of their father and grandmother but formally and systematically through I.C.S. correspondence courses ordered up from Earth. They would take with them spools enough to keep them busy for at least a year and mail their completed lessons from any port they might touch. Mr Stone was satisfied, being sure in his heart that any person skilled with mathematical tools could learn anything else he needed to know, with or without a master.
‘Now, boys, about this matter of cargo —’
The twins waited; he went on: ‘I’ll lift the stuff for you —’
‘Gee, Dad, that’s swell!’
‘— at cost. You figure it and I’ll check your figures. Don’t try to flummox me or I’ll stick on a penalty. If you’re going to be businessmen, don’t confuse the vocation with larceny.’
‘Right, sir. Uh… we still can’t order until we know where we are going.’
‘True. Well, how would Mars suit you, as the first stop?’
‘Mars?’ Both boys got far-away looks in their eyes; their lips moved soundlessly.
‘Well? Quit figuring your profits; you aren’t there yet.’
‘Mars? Mars is fine, Dad!’
‘Very well. One more thing: fail to keep up your studies and I won’t let you sell a tin whistle.’
‘Oh, we’ll study!’ The twins got out while they were ahead. Roger Stone looked at the closed door with a fond smile on his face, an expression he rarely let them see. Good boys! Thank heaven he hadn’t been saddled with a couple of obedient, well-behaved little nincompoops!
When the twins reached their own room Castor got down the general catalog of Four Planets Export. Pollux said, ‘Cas?’
‘Don’t bother me.’
‘Have you ever noticed that Dad always gets pushed around until he gets his own way?’
‘Sure. Hand me that slide rule.’
V — BICYCLES AND BLAST-OFF
The Rolling Stone was moved over to the spaceport by the port’s handling & spotting crew — over the protests of the twins, who wanted to rent a tractor and dolly and do it themselves. They offered to do so at half price, said price to be applied against freightage on their trade goods to Mars.
‘Insurance?’ inquired their father.
‘Well, not exactly,’ Pol answered.
“We’d carry our own risk,’ added Castor. ‘After all, we’ve got assets to cover it.’
But Roger Stone was not to be talked into it; he preferred, not unreasonably, to have the ticklish job done by bonded professionals. A spaceship on the ground is about as helpless and unwieldly as a beached whale. Sitting on her tail fins with her bow pointed at the sky and with her gyros dead a ship’s precarious balance is protected by her lateral jacks, slanting down in three directions. To drag her to a new position requires those jacks to be raised clear of the ground, leaving the ship ready to topple, vulnerable to any jar. The Rolling Stone had to be moved thus through a pass in the hills to the port ten miles away. First she was jacked higher until her fins were two feet off the ground, then a broad dolly was backed under her; to this she was clamped. The bottom handler ran the tractor; the top handler took position in the control room. With his eyes on a bubble level, his helmet hooked by wire phone to his mate, he nursed a control stick which let him keep the ship upright. A hydraulic mercury capsule was under each fin of the ship; by tilting the stick the top handler could force pressure into any capsule to offset any slight irregularity in the road.