A camera of the moving picture type, but set to snap one take at minute intervals, would check also; and if the seismograph got to zig-zagging sharply, it would make contact on one side with a relay, and throw on the “continuous” mechanism of the marvelous camera.
To discover by calculating how much of the tape had been unreeled when something had stopped it, was easy; and in that way Roger knew the time that the mechanism had stopped, although he did not dare fix that as the time the rats had vanished, because the tape had started at five in the afternoon, and had unreeled to the point to show that it had stopped at four in the morning; but the alarm had not sounded until half an hour or so later.
The tape showed excited swerves of the recording stylus, but not apparently enough to start the continuous takes, because Grover had left the magazine as it was until Potts should be ready to develop all prints at one time.
With his snapshots and time exposures of wide-angles of windows, doors, floors, air-conditioning intake, exhaust, cellar openings and floors, and his micrometric detail close-ups of parts of all these, Potts went to the dark-room adjoining Roger’s stock-room. The film he had taken would fill all tanks, so he left the other till later.
The authorities had been warned; and nothing more could be done.
Roger, as the sun rose, telephoned for light breakfast to be sent from a nearby restaurant, taking Potts his share in the dark-room.
As he ate, Roger tried to bring some sense into the baffling set of conditions:
The white rats, in their cage, with the observation apparatus and chart with notations, should have been recognized by anybody who could see and who could read, as dangerous to handle, much more to remove.
With the protecting system set, it should have been impossible to enter, at all, and more impossible to get out.
Yet the rats had not by any magic been evaporated into thin air.