“The record ended at that point, of course,” Ariel said.

“Yes. Since that time, witness records show that to be the pattern of blackbody operation in constructing the dome. As the construction progressed, the intersecting arcs traversed by the shimmer, and the point to which the blackbodies flew to begin each pass, rose in the air until it reached its present location. That operation now begins at midmorning at a height of a little more than a kilometer directly over the Compass Tower and lasts for one hundred twenty passes of the blackbodies, which generally takes a little over an hour.”

“Hour?”

“An ancient term from the vocabulary file. It means one-twenty-fourth part. The blackbody I conversed with used my access to central's files to search for an exact translation of their terminology, one-twenty-fourth part of the period of planetary rotation.”

“And do they divide that further, as we do with our centads?”

“Yes. Their next division, into sixty parts, can be labeled 'minutes' according to central. The conversion of those units into our decads and centads gives, for the hour…”

“I am quite capable of making that conversion, Wohler.”

“Thus construction of the dome begins each day at ten AM, and…”

“Ten AM?”

“At ten hours antemidday, or more exactly in the ancient terminology, ante meridiem, being before noon. Their day is divided into two twelve-hour parts: AM, before noon, and PM for post midday or after noon.”

“Didn't it seem odd to your alien that he could find terms that seem to describe their technology in our ancient history files?”

“No. By my recording, specifically in that regard, he remarked, 'How satisfying to find our own circadian rhythms-the metabolic divisions of our natural clocks-so faithfully reproduced in another species. ' “

“It seems darn odd to me,” Ariel said. “But to get on with this, at the time of the incident, the witness robot was sliced in half by the first elements of the present dome as its momentum carried it past the edge, just as the crowbar was cut in half earlier today.”

“Yes,” Wohler replied.

“You had had no interaction with the blackbodies until then,” Ariel said.

“That is correct.”

“But then you began a dialogue.”

“No. Not immediately.”

“But not to do so was to violate the Third Law, Wohler.”

“On the contrary, Miss Welsh, we chose to comply with the Third Law by retaliation.”

“But, Wohler, that violated the First Law, which protects intelligent life.”

“No, Miss Welsh, it does not. It protects humans.”

“It protects Wolruf. “

Wolruf was a dog-like alien, a friend of both Ariel and Derec. They had been through several unpleasant experiences together, starting with an alien pirate by the name of Aranimus who had held all three of them prisoner at one time. That was when they had first met Wolruf.

“But only because Master Derec chose to make an exception,” Wohler-9 said. “Dr. Avery's original programming made no such exceptions. The first law now protects humans and Wolruf. But our definition of a human being is quite narrow. It certainly does not include the blackbodies.”

Dr. Avery was Derec Avery's father and the erratic, egocentric scientist who had created the original planetary Robot City. He had suppressed his teenage son's memory and subjected him to irrational experiments in bizarre situations on and off the Robot City planet. Derec had learned a great deal about himself, but Avery left Robot City without restoring Derec's memory.

“Proceed, Wohler,” Ariel said. “How did you retaliate?”

“We attempted to stop construction of the dome by intercepting the flight path of the aliens, ramming them with a one-man flier, but it was not entirely successful. The alien was destroyed, but so was the flier and the robot pilot. Spectrographic and flame temperature records support a hydrogen explosion as the cause of failure.”

“So then you started a dialogue,” Ariel said.

“No. Logic dictated that we determine why a hydrogen explosion caused the failure, so we decided to trap and examine an alien.

“At night, the blackbodies convert into silver balloons which they anchor to the tops of trees. We successfully captured one which had anchored to a tree on the very edge of the forest five kilometers away. We easily unhooked its anchor line after cutting the tree down.

“However, in order to examine the alien, it was necessary to first remove the balloon which surrounded it. Again a hydrogen explosion destroyed the alien and the surgeon when he attempted to cut the balloon away with a laser scalpel.”

“It figures,” Ariel said with a sigh. “So then you initiated a dialogue. Surely.”

“No. One or more of the aliens had been confronting robots all around the Compass Tower construction site for three and a half days, but our programming did not require us to grant recognition, and we were, of course, quite busy erecting the Compass Tower, which had to be completed before work on the general city could begin. Understandably, we paid no attention to their confrontations, until I personally was confronted by one of the blackbodies. That happened immediately after we lost the surgeon and his laser scalpel. It then occurred to me, when I was confronted, that by conversing with the alien, I might find out what the surgeon was seeking, and I was then compelled by the Third Law to do so. The Third Law says…”

“I know, I know,” Ariel said. “So then you initiated the dialogue.”

“No. Surely it is clear by now, Miss Welsh, that the alien initiated the dialogue.”

“So it seems,” Ariel said with resignation coloring her voice. “I wouldn't want it any other way.”

“On the contrary. It is now quite apparent that if I had initiated the dialogue earlier…”

“You're quite right, Wohler. But you need not feel bad for all that.”

“I understand technically that you can be affected in that manner, but I am incapable of experiencing such an emotion, Miss Welsh.”

“Clearly,” Ariel said. “Clearly. Now what has your dialogue with this alien revealed?”

“Not a great deal, Miss Welsh. I have spent most of the time teaching him Galactic Standard, since I have no linguistic capacity for understanding his language. And teaching him has been most difficult because of that lack of linguistic knowledge. But he seems now to have a rudimentary knowledge of our language, which should prove useful in your dialogue with him.”

“I take it you are speaking of a male alien, then?”

“I loosely ascribe that gender, but it is more a description of his manner and conduct, a similarity to the attributes of a male human, which I perceive by the behavioral differences between the males and females of the human species.”

“Male chauvinism in a robot? Is that what I am detecting, Wohler?”

“Not at all, Miss Welsh. My analysis is quite objective.”

“On the contrary, Wohler. I would say it is quite programmed, and of the Dr. Avery variety. But let's get on. What else did you learn?”

“In reviewing my records,” Wohler replied, “I found that I taught the alien our language and much about humans, but learned little about them, other than the fact that the construction of our city is disturbing their equilibrium. He used the terms inversions and puncture nodes and abnormal thermoclines, but the terms have little meaning for me, and so little meaning for me to pass on to you.”

“The terms do not help me a great deal, either,” Ariel said. “Do they mean anything to you, Jacob?”

Up to that point, Jacob in his niche had not entered into the conversation, nor moved at all. He had appeared frozen in position. Now his head gave a little twitch. A glimmer came into his eyes.

“They are meteorological terms, Miss Ariel,” Jacob said. “Like in weather?”

“Yes.”

“We're disturbing their weather!” she exclaimed.