Simulated Triangulation

Yesterday, Rome, Rei and MINIMCOM contacted Aason who has been kidnapped and taken away to Socal, southern California. Rei had him sing the Inky Dinky Spider song so they could find the point of highest signal strength indicating Aason's line of longitude. However to actually locate him, they are going to have to employ some geometry to find the proper latitude, the mid-line of signal strength. They must travel up and down finalizing the coordinates until they spot the boy:

     “We don’t need to,” Rei interjected. “We’ll wing it. Just drift north together and see if the signal increases or decreases.”
     “And the inky dinky spider climbed up the spout again.”
     “It is decreasing,” MINIMCOM said.
     “Great,” Rei said. “Now both of you drift south and stop when the signal peaks. Kind of a simulated triangulation.”
     “Of course,” MINIMCOM replied.
     Rei was not an expert on California but as far as he could tell, they were near the area that used to be known as Long Beach. Directly below them was a river, probably the Los Angeles River. It was a dead-straight vertical stripe that ran north to south. The ventral cameras showed them following the river’s path as it made its way toward the Pacific. They were about five miles from the coast when MINIMCOM announced they were roughly over Aason’s position.
     “You can stop singing now, Aason,” Rome said. They studied the images on the ventral cameras. There were grasslands and a heavy stand of trees clustered in the area. MINIMCOM switched one monitor to infrared and another to ground penetrating mode. It quickly became apparent that there was entire community covered mostly by the trees. The infrared showed several people walking about. There were far too many houses to deduce which one held their son.
     Rome stood up. “I want to go down there,” she said insistently.
     “Hold on,” Rei cautioned. “This whole thing has been a trap since Day 1 and you’re going to walk right into it.”
     “What do you suggest?”
     Rei stared down at the monitors for a moment. He called to his son. “Aason, do they let you go outside to play?”
     “Sometimes,” he said. “But if I go out, somebody always follows me.”
     “That’s OK,” Rei said. “Do you know the woman they call Reema?” he asked.
     “Yes,” Aason answered. “She comes in to see me every day. She always seems angry, though.”
     Rei laughed. “Good. I’m glad she is angry. When does she come in to visit you?”
     Aason didn’t answer for a second then said, “Pretty soon. She usually comes in the afternoon.”
     “OK, Son, here’s what I want you to do. Is there anything in the room that is really shiny? Like glass?”
     “There are some tubes here,” Aason replied. “I’m not supposed to touch them.”
     “I’m giving you permission,” Rei said. “This is what I want you to do…”

It seems like an elaborate plan. How will Rei use the tube to find Reema? You'll see tomorrow.