Lenning was not in the vicinity of the first row, and Frank dropped to the next tier. He wasn’t there, either. In spite of the gloomy shadows cast by the big vats, the lad was able to see with tolerable clearness. The third and last row remained to be investigated, but here the same ill luck rewarded Frank’s search. Lenning was not in evidence around the tanks.
Possibly, Frank thought, the new watchman might be in the mill. Or, if he was not there, some of the night shift might know where he could be found. Just as Frank was turning to start for the mill, he saw a flash of light through one of the windows of the laboratory. He halted and stared, a trifle bewildered.
Not five minutes before he had looked at the laboratory, and the windows had all been dark. How did it happen that now there was a light in one of them?
“Not much of a mystery about that,” he finally decided. “Some one has gone into the place and lighted a lamp. It may be Lenning; or, if not Lenning, then some one who has been helping with the clean-up. I’ll——”
The muttered words died on Frank’s lips. Under his eyes, as he continued to watch the window, the light winked out and again left the laboratory in darkness.
“I guess that’s easily explained, too,” he presently decided. “The fellow that lighted the lamp put it out again. It was Lenning, of course. As I went hunting for him among the tanks, he had to go to the laboratory for something. That’s how I happened to miss him. He has got what he wanted, and so he has put out the light and will soon be coming back. I’ll wait here for him.”
Frank kept his eyes fixed on the dark side of the laboratory building, where he knew the door was located. Every moment he expected Lenning to appear, walking toward him out of the shadow of the laboratory wall. But the seconds grew into minutes, and still Lenning did not come. The waiting lad was forced to the conclusion that there was something strange about all this.
“If there’s anything wrong,” he thought, “I ought to find the superintendent, and report. But how do I know there is anything wrong? Maybe all I see is a part of the night’s work, and if I went to the super he’d only have the laugh on me. I’d better investigate a little before I spread any news of trouble.”
The roaring mill, with its glittering lights, suggested quick help in the case of emergency. Frank had a vague notion that it would be well to go there and make some inquiries before investigating the laboratory. But, if he went to the mill, the fellow who had struck a light in the laboratory would have time to come out and get away unseen. If it was Lenning, then he would miss him, and would have to begin his search all over.
Another thought came to him, as he moved slowly upon the laboratory, and Frank was surprised that it had not occurred to him before. A night watchman, moving about among those dark tanks, would certainly carry a lantern. Frank had been stumbling blindly around the tanks, hunting for Lenning, when, if he had considered the matter thoroughly, he need only have looked for a bobbing light.