the foul mixed with the pure. The poisons move out slowly from where they were born. And the vapors of which I speak fill a very large volume. Even though a lithosoar can fly for many sleeps on a drifting course if its supply of marrow is high, no Skyskirr can hold shut his lips for as long as it takes to pass through such a cloud.'
Ponzar waved his small shovel in front of Jemidon's face. 'The great right hand guides. It is the duty for all the Skyskirr to follow. Whatever happens is by his design. And I have a duty, as shown by my token of office. The pilot uses his key for the unlocking. The manipulants chip precious lodestones from baser rocks with their picks. The others, the scribes, the smiths, the skinners, all have their duties and tokens as well. And the captain of a lithosoar must scoop the treasures from the skies and provide for his people so that marrow is for feasting and not survival in the voids.'
For a moment Ponzar sank into silence, oblivious to the fact that Jemidon was even there. Then he rose abruptly, apparently satisfied with the conversation. In the doorway, he shifted his shovel to his left hand. He extended his right index finger pointing at Jemidon, thumb upward and middle finger bent to the side. Jemidon returned the signal as he had been taught.
When the captain had gone, Jemidon turned his attention back to the coin changer and sighed. There was nothing else for him to do but wait. 'If I start with three silvers before the galleons,' he muttered, 'then the first brandel will fall into the third column. That means that a dranbot must be next to deposit into the fifth.'
Jemidon felt the slight tremble as their small boulder began to slow in its passage, rather than continuing to hurl past the larger sphere. Compared with the agonizing slowness during over a dozen sleeping periods with which their target had come into view, first as an indistinct speck and then gradually growing into a discernible disk, the motion now seemed rapid indeed. He knew that soon they would reach a perilith, then loop back in a long ellipse. Ponzar had said that the trade delegation would come when they were almost skimming the surface.
Already the other lithon blotted out a good portion of the sky, fissures and crags becoming more distinct with each passing moment. Details were more regular, indicating the effort of intelligent minds. Larger squares of greens and blues checkered a relatively flat plane. Up-thrusts of rock were sculptured with spiraling steps. Hundreds of lights blinked in small clusters that covered the orb like a great pox.
Jemidon and Delia stood with the Skyskirr, awaiting the arrival, crammed among sacks of bones, twisted branches of trees, wagonloads of sparkling rock, and other objects that Ponzar's group had scavenged in their trek across the sky.
Jemidon twisted restlessly as the large sphere gradually drew closer. He had been able to deduce some additional facts about his surroundings, but even more time in his own universe had been lost as the lithons converged. With no periodic repetitions in the heavens, he could not be sure how much. But at least Melizar's djinn had not reappeared. Now, with contact with other Skyskirr imminent, perhaps he could find something more than bare rock to bridge the gap to the demon realm and home.
'I still do not understand about the forces between the special stones,' Delia said at his side. 'How do their attractions affect the direction in which we will go?'
Jemidon smiled at the sweetness in her voice. For most of their journey, she had remained to herself, gladly accepting a separate cavern when it was offered. Now, like a weathervane, her charm was again pointing his way.
'It is the construction of this universe,' Jemidon answered. He grabbed a shovel from her hand and with its blade scratched a crude figure in the surface of the rock. 'Ponzar is reluctant to say much; but from his small slips and what we have seen, I have figured out much of their laws.'
'You know the third metalaw?' Delia's face brightened. 'Does it provide the means to see us back?'
'Just laws, not metalaws.' Jemidon shook his head. 'It all began to make sense when I finally recognized the pattern of the distant lines in the sky.' Jemidon looked upward and nodded his head. He had carefully walked all over the surface of the Jithosoar and seen them all. There could be no other answer. 'We are in a box, Delia-a giant icosahedron, it properly would be called, a regular solid with twenty triangular sides. All that the Skyskirr know to exist lies within the walls of this crystal. From the triangular surfaces they get light and heat. The closure of the 'hedron keeps the air from whirling away to whatever is beyond.'
'Like the edges of the world in our own sagas?' Delia asked. 'If you sailed too close, you ran the risk of falling over the side.'
'Here the risk is not one of falling off,' Jemidon said, 'but of never being able to return. I suspect that the planes are covered with the lodestones that the scavengers find so dear.'
'It is these rocks that pull them through the air?'
'Exactly so,' Jemidon said. 'Positive cairngorm is attracted by one of the plates and repulsed by another on the othtr side of the 'hedron. For negative cairngorm, the effect is the reverse. Even when it is near no other sphere, a lithosoar can be accelerated by the forces between the walls.
'There are twenty faces in all and ten opposite pairs. For each pair, there is a corresponding rock: black sphalerite, violet spinel, rusty cairngorm, orphiment, realgar, anatase, chrysocoHa, epidote, beryl, and serpentine. I have seen the rocks on the tablestone and as they have spilled from the manipulants' pouches-ten types of lodestones in both positive and negative varieties. And for each type, a rock of one variety is attracted to those which are opposite and repulsed by those which are the same. The force falls off with some power of the distance.'
Jemidon paused and contorted his hand in the sign of greeting. 'Actually, it is a little more complicated than that. Two additional plates interact with each type of lodestone as well. But only when it is moving and at an angle to the direction of motion. It is the meaning of the right hand. If the thumb points in the direction of the primary tug and the forefinger in the direction the lodestone is moving, then the additional force will be in the direction of the curling fingers. The extended fingers of the hand are a simple mnemonic from a distant past to aid in the calculation of trajectories. If there were only one lode-stone and no others to perturb its path, its motion would be a helix that would eventually reach one of the walls.'
'But our flights are anything but so simple,' Delia said. 'Utothaz maneuvered us almost at will.'
'There are other bodies in the 'hedron as well, each with its own complement of rocks that attract and repel.'
'But what of the control?' Delia asked. 'He maneuvered our lithosoar over the other as if we were a docile bird.'
'It is the-the metamagic. Yes, that is the word for it,' Jemidon said. 'The laws of attraction for the stones can be turned on and off at will. To approach a target, you invigorate the law that attracts the two bodies together. To break before collision, you switch instead to one that repels. Far away from any lithon, you rely on the forces between the walls. Indeed, that is the role of the metamagician in this domain. He is the pilot who calculates the courses and steers the scavengers through the sky, guiding them from one stone to the next to collect whatever of value they can. The laws themselves are simple. Attraction or repulsion, falling with distance, and a second force at right angles to the velocity. Once a law is in effect, it permeates the entire universe; but with a few observations, anyone can calculate the trajectories that result. There is little of the arts as we know them here, Delia. No complex rituals or incantations that only a master can control. It is metamagic instead that is supreme.'
Jemidon broke off and pointed skyward. A swarm of small figures rose from the surface of the larger lithon and accelerated swiftly to catch their lithon as it hurled past. When the visitors grew closer, Jemidon saw that they looked much like Ponzar and the rest, dressed only in loincloths, despite the stinging cold. Each carried a huge pack on his back, and a copper sword dangled from his side. Arms were extended directly forward. In one hand, each held a fair-sized stone of blue that seemed to pull its owner along; in the other was an inert crystal of black.
Partway on their intercept trajectory, Jemidon experienced the feeling of disconnection. It was stronger than any since Utothaz's sweep of the beasts, but the disorientation was totally under control. It was merely an irritation that he hardly noticed any more,
'They have deactivated the attraction of the blue stone and changed to the repulsion of the black,' he said. 'When they arrive, their relative speed will be almost zero. Then the law will be shifted to another and the lodestones will have no special powers until they are reactivated for their return.'
In a few minutes, Ponzar climbed with a slow, careful step to where the first visitor had landed. He signaled with a finger-bent right hand and ordered the security of a well-anchored rope. The new arrival accepted the
