Davis, Evelyn, and Teddy were discussing the matter dolefully. Davis had been coming to the laboratory daily in the hopes of hearing that Teddy had devised some plan for the frustration of Varrhus' ambitious schemes. Teddy found himself liking Davis immensely, but with a peculiarly illogical annoyance that Evelyn seemed to like him quite as well. When he had phoned her of his safety after the fight with Varrhus he could hear a flood of thankfulness in her voice, but when he saw her the next day she was almost distant. He saw traces of real anxiety on her face, but she had not been really natural until they had worked nearly all day on the silver bracelet, trying to find what had been done to the surface to give it its peculiar property of allowing heat to pass in one direction, but not in the other. They were as far as ever from the solution. Davis was quite ignorant of abstract chemistry or physics and could not join in their discussions, but Teddy fancied that he was much more interested in Evelyn than was necessary. He was annoyed to find that he resented it. He had always looked on Evelyn as a comrade, and he could not understand this feeling that took possession of him. It did not occur to him to speculate upon the fact that he found ideas coming to him much more readily when working by Evelyn's side, or that he rarely attempted anything without asking her opinion. Teddy had never thought much of romance, and he did not suspect how much Evelyn's companionship meant to him. Davis was reiterating for the fortieth time his disappointment at Varrhus' getting away. "We almost had him," he said disgustedly. "Our explosive bullets were playing all over his infernal flying machine. We'd have landed one in that little glass cabin of his and smashed him nicely in another minute, when he skipped off like that. And I'll swear to it we were doing a hundred and eighty miles an hour." "He ran away from us pretty easily," said Teddy dismally. "Isn't there a faster machine than yours we could get hold of?" "Nothing but a single-seater, and not so much faster at that," said Davis. "A hundred and ninety-five is the best even the latest single-seater combat planes will do at a low altitude." "Even for a short burst of speed?" asked Evelyn. "Diving, you'll run up faster than that," Davis explained. "When we went straight down after Varrhus, we must have gone over two hundred, but for straightaway work we've nothing that will catch Varrhus." "What's the official speed record?" asked Evelyn, toying with a test tube. She looked singularly pretty in the long white apron she wore in the laboratory. "Two hundred and fifteen, I think," said Davis. "Some Spanish aviator made it. He'd doped his gas with picric acid, though." "What does that do?" asked Teddy quickly.