One day, during the Reign of Terror following the French Revolution, the executions of three men were scheduled: A priest, a lawyer, and an engineer.
It was the priest's turn first. He was asked if he had a final request.
"Yes," he said. "I know it is unusual, but I would like to be executed facing up so that the last thing I will see will be the heavens. "
The executioner honored his request, and placed him in the guillotine face up. The executioner pulled the lever. The blade fell toward the priest, but it stopped a quarter-inch from his throat.
At that point, the lawyer stepped forward with a lawbook he had pulled out of his pocket, and read a passage proving that, once the lever has been pulled, the execution may not be repeated. They had to release the priest.
Now it was the lawyer's turn. For his last request, figuring that it had brought the priest good luck, he also asked to be placed face up. Again, the blade stopped short, and the lawyer had to be released.
Next, the engineer, figuring it had worked well for both the priest and the lawyer, asked to be placed face up on the guillotine. The executioner got ready to pull the lever. But before he could, the engineer exlaimed:
"Wait, I see the problem! See that spring up there? It has come loose. All you have to do is attach it, and the device will work fine!"