“So to multiply two numbers—let us say three and two—you move the left index to the three and set the cursor on the two.” She demonstrated, her fingers working with a swift, practiced precision. “Then you can read the answer from the bottom scale.”
He looked down. “Six,” he said.
“Excellent.” Her tone was almost brisk and business-like—almost, but for that slight hint of a quaver in it. “Now I shall write out a few problems. I expect you to calculate them using the slide rule.”
She took out a piece of paper and began writing numbers down the side—lots of numbers, as if he were a child tasked with working problems. She wrote swiftly, in a clear, defined hand and slid the page over to him.
He knew he had an effect on her—the same effect he had on most women. He could dazzle her temporarily. But she did not stay dazzled, and he was not used to being so flummoxed in response.
“Let me know when you’re finished,” she said.
He looked at the paper. “You’re not going to multiply with me?”
“No,” she said somewhat severely. “You’re going to multiply on your own. But I’ll make you a wager. If I can finish my calculation of the projected cometary trajectory without the use of my slide rule before you can multiply a few piddling two-digit numbers…”
He took the paper from her. “What will I win, then?”
“Another lesson on multiplication.”
He laughed softly. “And if I don’t?”
“Then we’ll head straight to division,” she said briskly.
So saying, she opened her portfolio. He saw a bewildering column of numbers—interspersed with a few Greek deltas and epsilons—before she bent her head over them.
He’d heard her talk about her work. She’d occasionally done complicated long division in her head as she explained something to him on the streets. He’d known she was a genius—she spilled genius all around her without even having to think of it. But watching her work was one of the most astonishing things he had ever witnessed.
The paper was divided into five columns, each carefully labeled. She had to have been multiplying nine-digit numbers in her head without a moment’s hesitation, marking them down on the paper as swiftly as she could write. He vaguely recognized something that he thought might have been the gravitational constant, if only his woeful knowledge of dimly recalled physics meant something…
“You’re not multiplying,” she said severely. But she didn’t look at him. Instead, she adjusted her spectacles on her nose.
“Miss Sweetly, why on earth do you even have a slide rule?” he asked in amazement.
She still didn’t look up. “There are trigonometric functions on the reverse of the slide. And occasionally, I need it as an aid to correct someone who believes I might be wrong.” She frowned. “Mostly, though, I find it comforting.”
He shook his head and started on his multiplication.
She did not finish before him—even though she’d filled four pages of calculations and had marked a cometary path about ten degrees further along. It was obvious that she had not intended to finish before him. She’d made that little wager as a sop to his pride. Boasting that he had finished first would have been like a child sketching a line drawing of a man, and then crowing that it had taken less time than it had taken Michelangelo to complete the Sistine Chapel.
He sat and watched her figure instead.
He knew Miss Sweetly was charmed by him. She was too nervous in his company not to be. When they talked, she winced as she spoke, sometimes shaking her head as if to contradict her own words. It was only when she talked mathematics that he could see this side of her—sure and steady, swift and beautiful, as if when she was surrounded by numbers, she forgot that she was supposed to be shy.
Behind them, he could hear Mrs. Barnstable snoring. Precisely as Miss Sweetly had predicted.
She looked up after a moment and noticed that he was done. She glanced over his paper with a practiced eye.
“That proved easy enough,” she said.
“What is next, Miss Sweetly? You did promise me more multiplication.”
She nodded. She had lost that air of uncertainty; she was in her mathematical element now, and it showed.
“Let us calculate a very small number,” she said. “How about a probability? Do you know much of probabilities?”
“A little.” He made a motion with his hand.
“Well, then. I’ll make this one simple. What do you suppose the chances are that I will be foolish?”
He looked over at her. “Shy?” he asked. “Or stupid?”
She winced a little at that, but didn’t look away. “The latter, if you please.”
“Then I’d put it at no better than one in a thousand.”
“Very well, then. Multiply that by the possibility of our meeting while alone—let us call that one in four—and that by the chance that you will be charming.”
His interest was piqued now. He had no idea what she was computing, but he’d be happy to find her alone and charm her into whatever number she wished. He leaned forward. “Tell me. What is the chance that you’ll find me charming?”
“I’d approximate it as…” She looked across the room thoughtfully, her finger tapping against her lips. “I suppose I should be generous; you are paying for these lessons. So let us say forty percent.”
“A mere forty percent?” Stephen clutched his chest dramatically. “A knife to the heart! You slay me, Miss Sweetly.”
Her finger did not stop tapping, but she smiled as shyly as if he’d offered her a compliment. “You misidentify the weapon. It’s not a knife.”
“No?”
Miss Sweetly shook her head. “It’s a double slide rule from Elliots, and I have found it extremely useful in dispatching all manner of men. Especially the ones given to excess histrionics. Now shall we continue the calculation?”
He sat back, smiling faintly. “By all means. I can see where this is heading. I have always wanted to be abused with numbers.”
She huffed. “The chance that my father would not discover the whole thing before it proved too late is one in ten, and the possibility that I should be hit on the head with an anvil, or a similarly heavy item, is perhaps one in a million. Tell me, Mr. Shaughnessy, what is the probability of all those things occurring in conjunction?”
“Ah…” He had to use paper to keep track. “That would be…a chance of one in…a hundred billion?”