"A slight touch of emergency rocket," said Calhoun. "They've run away. Now we end the plague on Tallien Three."
The grid operator was still dazed by the continued absence of any indication that he might ever become a para. He said unsteadily:
"Sure! Sure! But how?"
"Wood smoke," said Calhoun. "Emergency rockets. Roofs! There's been no wood smoke in the air on this planet because there are no forest fires and people don't burn fuel. They use electricity. So we start the largest production of wood smoke that we find convenient, and the population of a certain modified butyl mercaptan molecule will be reduced. Down to a normal level. Immediately!"
The emergency rocket bellowed thunderously and the little Med Ship rose.
There have been, of course, emergency measures against contagion all through human history. There was a king of France, on Earth, who had all the lepers in his kingdom killed. There have been ships and houses burned to drive out plague, and quarantines which simply interfered with human beings were countless. Calhoun's measure on Tallien was somewhat more dramatic than most, but it had good justification.
He set fire to the planet's capital city. The little Med Ship swept over the darkened buildings. Her emergency rockets made thin pencils of flame two hundred feet long. She touched off roofs to the east, and Calhoun rose to see which way the wind blew. He descended and touched here and there....
Thick, seemingly suffocating masses of wood smoke flowed over the city. They were not actually strangling, but they created panic. There was fighting in Government Center, but it stopped when the mysterious stuff—not one man in a hundred had ever seen burning wood or smelled its smoke—the fighting stopped and all men fled when a choking, reeking blanket rolled over the city and lay there.
It wasn't a great fire, considering everything. Less than ten per cent of the city burned, but ninety-odd per cent of the paras in it ceased to be paras. More, they had suddenly regained an invincible aversion to the smell of butyl mercaptan—even a modified butyl mercaptan—and it was promptly discovered that no normal who had smelled wood smoke became a para. So all the towns and even individual farmhouses would hereafter make sure that there was pungent wood smoke to be smelled from time to time by everybody.