When I was a small boy," said Patrick O'Brian wistfully, "I used to love coming up here to watch the magic pictures. They seemed so much brighter - and more interesting - than the real world outside. No telly in those days, of course - and the travelling tent cinema only came to the village about once a month."

"Don't you believe a word, Jason," said Donald Craig. "Pat isn't really a hundred years old."

Though Bradley would have guessed seventy-five, O'Brian might well be in his eighties. So he must have been born in the 1930s - perhaps even the '20s. The world of his youth already seemed unimaginably remote; reality outdid storytelling exaggeration, even by Irish standards.

Pat shook his head sadly, as he continued pulling on the cord that rotated the big lens five metres above their heads. On the matte-white table around which they were standing, the lawns and flowerbeds and gravel paths of Conroy Castle performed a stately pirouette. Everything was unnaturally bright and clear, and Bradley could well imagine that to a boy this beautiful old machine must have transformed the familiar outside world into an enchanted fairyland.

"'Tis a shame, Mr. Bradley, that Master Donald doesn't know the truth when he hears it. I could tell him stories of the old lord - but what's the use?"

"You tell them to Ada, anyway."

"Sure - and she believes me, sensible girl."

"So do I - sometimes. Like those about Lord Dunsany."

"Only after you'd checked up on me with Father McMullen."

"Dunsany? The author?" asked Bradley.

"Yes. You've read him?"

"Er - no. But he was a great friend of Dr. Beebe - the first man to go down half a mile. That's how I know the name."

"Well, you should read his stories - especially the ones about the sea. Pat says he often came here, to play chess with Lord Conroy."

"Dunsany was grand master of Ireland," Patrick added. "But he was also a very kind man. So he always let the old lord win - just. How he'd have loved to play against your computer! Especially as he wrote a story about a chess-playing machine."

"He did?"

"Well, not exactly a machine; maybe an imp."

"What's it called? I must look it up."

"The Three Sailors' Gambit- ah, there she is! I might have guessed."

The old man's voice had softened appreciably as the little boat came into the field of view. It was drifting in lazy circles at the centre of a fair-sized lake, and its sole occupant appeared to be completely engrossed in a book.

Donald Craig raised his wristcom and whispered: "Ada - we have a visitor - we'll be down in a minute." The distant figure waved a languid hand, and continued reading. Then it dwindled swiftly away as Donald zoomed the camera obscura lens.

Now Bradley could see that the lake was approximately heart-shaped, connected to a smaller, circular pond where the point of the heart should have been. That in turn opened into a third and much smaller pond, also circular. It was a curious arrangement, and obviously a recent one; the lawn still bore the scars of earth-moving machines.

"Welcome to Lake Mandelbrot," said Patrick, with noticeable lack of enthusiasm. "And be careful, Mr. Bradley - don't encourage her to explain it to you."

"I don't think," said Donald, "that any encouragement will be necessary. But let's go down and find out."