He stopped fidgeting with the recorder; the mood of maudlin self-pity was over. Releasing the elastic webbing that held him to his seat, he set off for the technical stores in search of the materials he needed.

“This,” said Dr Martens three days later, “isn’t my idea of a joke.” He gave a contemptuous glance at the flimsy structure of wire and wood that Pickett was holding in his hand.

“I guessed you’d say that,” Pickett replied, keeping his temper under control. “But please listen to me for a minute. My grandmother was Japanese, and when I was a kid she told me a story that I’d completely forgotten about until this week. I think it may save our lives.

“Sometime after the Second World War, there was a contest between an American with an electric desk calculator and a Japanese using an abacus like this. The abacus won.”

“Then it must have been a poor desk machine, or an incompetent operator.”

“They used the best in the U.S. Army. But let’s stop arguing. Give me a test—say a couple of three-figure numbers to multiply.”

“Oh—856 times 437.”

Pickett’s fingers danced over the beads, sliding them up and down the wires with lightning speed. There were twelve wires in all, so that the abacus could handle numbers up to 999,999,999,999—or could be divided into separate sections where several independent calculations could be carried out simultaneously.

“374072,” said Pickett, after an incredibly brief interval of time. “Now see how long you take to do it, with pencil and paper.”

There was a much longer delay before Martens, who like most mathematicians was poor at arithmetic, called out “375072”. A hasty check soon confirmed that Martens had taken at least three times as long as Pickett to arrive at the wrong answer.

The atronomer’s face was a study in mingled chagrin, astonishment, and curiosity.