Let me modify the illustration to bring it closer in alignment with Watchtower history.
At 10pm the personnel in the lookout tower observe a number of general signs in the environment: an absence of animal noises, difficulty in seeing stars, a slight increase in nighttime temperature compared to the night before, and a jeep sighted a few hours earlier on one of the roads. The staff surmise that these are positive indications that a fire will happen (animals being afraid of the fire, smoke obscuring the stars, heat from the fire, and a suspected arsonist), and that an arsonist is invisibly present in the forest below. They telephone the firefighters, telling them that there is postively an arsonist in the woods below and within 40 minutes, he will start a fire that will sweep through the whole forest. The plea goes out so that the firefighters will be ready when the fire actually starts.
Then 40 minutes passes. At 10:40pm everyone waits to see the first signs of smoke. But there is no smoke, no fire. A loud bang however did ring out at 10:39pm. The tower personnel take this as confirming that indeed an arsonist is invisibly present and did indeed start the fire somewhere, invisibly. The firefighters however are more skeptical, thinking someone shot a gun, or a car on a distant road had a backfire. The tower personnel maintain their belief that the fire has already started, and they continue to scan the woods to see any trace of smoke. At 11:45pm, the lead lookout person on duty, the one who made the phone call to the fire suppresion crew, signed off and retired for the night. His replacement was the night shift lookout person, who observed the preceding events. As soon as he starts duty, he rings the firefighters to tell them that the fire which started at 10:40pm will in fact blaze forth at midnight. He then made about 20 phone calls in the next ten minutes to the governor, the three major TV networks, NPR, and every other media person he had a number for. A swarm of news choppers surrounded the tower, prepared to give live news coverage of the fire when it blazes forth. At midnight, nothing happens.
Without even waiting to see if anything happens, the night watcher called the firefighters and told them confidently that there never was any arsonist around at 10pm; it was the loud bang at 10:39pm that indicated that the arsonist was invisibly present. He refused to say when the fire would actually start, but he assured everyone that it will happen before his shift was over.
At 6am, he signed off and went home.
The morning shift took over and called the annoyed firefighters, telling them that they now confidently expect that the fire will start at 8pm later that evening.
Meanwhile, the morning shift was interviewed by the media over the decable and they state that earlier people on duty were mistaken but should be commended for their good intentions in being alert. They also specifically denied that there ever was any statement that the arsonist was present at 10pm; they insisted that they have always expected that the arsonist would arrive around 10:40pm.
The day passes uneventfully. And nothing happens at 8pm.
But the night is still warm and no animals were heard in the distance. The arsonist, the tower staff noted, must be very close.
