He lay at full length in the paved alley and thought that a little acquaintance with Weintraub would go a long way.  Then the light in the window above him went out, and he gathered himself together for quick motion if necessary.  Perhaps the man would come out to close the cellar door——­

The thought was in his mind when a light flashed on farther down the passage, between him and the kitchen.  It came from a small barred window on the ground level.  Evidently the druggist had gone down into the cellar.  Aubrey crawled silently along toward the yard.  Reaching the lit pane he lay against the wall and looked in.

The window was too grimed for him to see clearly, but what he could make out had the appearance of a chemical laboratory and machine shop combined.  A long work bench was lit by several electrics.  On it he saw glass vials of odd shapes, and a medley of tools.  Sheets of tin, lengths of lead pipe, gas burners, a vise, boilers and cylinders, tall jars of coloured fluids.  He could hear a dull humming sound, which he surmised came from some sort of revolving tool which he could see was run by a belt from a motor.  On trying to spy more clearly he found that what he had taken for dirt was a coat of whitewash which had been applied to the window on the inside, but the coating had worn away in one spot which gave him a loophole.  What surprised him most was to spy the covers of a number of books strewn about the work table.  One, he was ready to swear, was the Cromwell.  He knew that bright blue cloth by this time.

For the second time that evening Aubrey wished for the presence of one of his former instructors.  “I wish I had my old chemistry professor here,” he thought.  “I’d like to know what this bird is up to.  I’d hate to swallow one of his prescriptions.”

His teeth were chattering after the long exposure and he was wet through from lying in the little gutter that apparently drained off from the sink in Weintraub’s prescription laboratory.  He could not see what the druggist was doing in the cellar, for the man’s broad back was turned toward him.  He felt as though he had had quite enough thrills for one evening.  Creeping along he found his way back to the yard, and stepped cautiously among the empty boxes with which it was strewn.  An elevated train rumbled overhead, and he watched the brightly lighted cars swing by.  While the train roared above him, he scrambled up the fence and dropped down into the alley.

“Well,” he thought, “I’d give full-page space, preferred position, in the magazine Ben Franklin founded to the guy that’d tell me what’s going on at this grand bolshevik headquarters.  It looks to me as though they’re getting ready to blow the Octagon Hotel off the map.”