“You realize, A.R., that there isn’t the slightest chance of getting away with this hoax? There’s so much stuff here that I can easily tell whether it’s genuine. Can I borrow these tables for a couple of days?”

“Kingsley, if you imagine that I would go to the trouble of staging an elaborate — hoax as you call it, primarily with the object of deceiving you, of taking a rise out of you, then all I can say is that you flatter yourself unduly.”

“Let’s put it this way,” answered Kingsley. “There are two hypotheses that I can make. Both at first sight seem incredible, but one of them must be right. One hypothesis is that a hitherto unknown body with a mass of the same order as Jupiter has invaded the solar system. The second hypothesis is that the Astronomer Royal has taken leave of his senses. I don’t want to give offence, but quite frankly the second alternative seems to me less incredible than the first.”

“What I admire about you, Kingsley, is the way you refuse to mince matters — curious phrase that.” The Astronomer Royal reflected thoughtfully for a moment. “You should go in for politics one day.”

Kingsley grinned. “Can I have these tables for a couple of days?”

“What do you propose to do?”

“Well, two things. I can check the consistency of the whole business and then I’ll find out just where the intruding body is located.”

“And you’ll do this how?”

“First I’ll work backwards from the observations of one of the planets — Saturn might be the best one to choose. This’ll determine the distribution of the intruding body, or intruding material if it isn’t in the form of a discrete body. This’ll be much the same thing as the J. C. Adams — Le Verrier determination of the position of Neptune. Then once I’ve got the intruding material pinned down, I’ll work the calculation forwards. I’ll work out the disturbances of the other planets Jupiter, Uranus, Neptune, Mars, etcetera. And when I’ve done that, I’ll compare my results with your observations of these other planets. If my results agree with the observations then I’ll know there’s no hoax. But if they don’t agree — well!”