“Ah.”

“In any event, Finlay in Cape Town wired his measurements to Dr. Barnstable, and he’s set me to do the computing.”

“So what does it look like?”

She got out her notebook, opened it to the appropriate page.

“Here we are. The comet transited the sun a month ago.”

He stared for a moment at the column of numbers she was pointing to, and then gave his head a shake. “Right.”

She felt herself flush again. But before she could manage to work up a good case of embarrassment, he had interrupted her, pointing to an orange in her bag.

“So let’s say that is the sun. Then where is the comet?”

“Don’t be ridiculous, Mr. Shaughnessy. If that orange represents the sun, we here on earth would be standing seventy-one feet away.”

“Seventy-one?” he asked mildly.

“Seventy-one point five eight three, by the last measure of the distance between the earth and the sun, but I try not to be pedantic. It makes people laugh at me.” Rose pointed to a dot on her notebook page. “Imagine that this is the sun. Then we are a speck of unimaginable smallness here.” She indicated a spot some inches away. “The comet, then, traveled along this path…” Her finger, dark against the white page, etched an elliptical curve. “But that’s not the exciting part. You see, anyone can calculate the path of a comet given enough data.”

“Not anyone,” he murmured.

She waved this away. “From all accounts, the nucleus of this comet split sometime after perihelion. Dr. Barnstable believes that we can predict the path of each piece—and since they’re so close to each other now, it will be no simple matter. It’s a three-body problem, which means it’s impossible to solve with equations. He’s asked me to work it out for him.” She beamed up at him.

He smiled back. “That’s brilliant, Miss Sweetly.”

“Of course,” she started to explain, “we’ll be wrong, but it’s how we’re wrong that is most exciting. You see—”

The door opened behind them. Rose jumped again. This time, she managed to keep hold of her shopping bag. She turned to see her sister standing in the doorway. Patricia had one hand on the door handle; the other was placed in the small of her back. She was wearing a voluminous pink gown and a matching kerchief covering her hair. Her eyebrows rose at the scene in front of her, but her dark eyes sparkled in amusement.

“And here I thought I heard you at the door ages ago,” Patricia said. She gave her a head an exasperated shake, but Rose was certain—mostly certain—that she smiled as she did it. Patricia stooped as best as she could. Her heavy belly made her awkward, but she plucked Rose’s key off the ground. “Ah. I see that I did.”

“I…dropped some things,” Rose said, flushing all over again. “I was picking them up.”

Patricia looked at Rose’s notebook, open in her hands. She looked at Mr. Shaughnessy, standing not two feet away. And then she glanced at the pavement, where Rose’s other packages—the mail, the paper, the wrapped-up book—still lay scattered. “Yes,” she said dryly. “I can see that. That explains everything.”

“I’ll let you go, then,” Mr. Shaughnessy said. He tipped his hat. “Miss Sweetly. Mrs. Wells.”

“Mr. Shaughnessy.” Rose nodded her head. “I would curtsey, but the apples cannot withstand another inelastic collision.”

Beside her, Patricia made a noise in protest. But she held out her hands, gesturing. Rose gave her the book and her slide rule case. While Mr. Shaughnessy disappeared around the corner of the street, she picked up the last of her scattered things.

Patricia did not berate her immediately. She did not, in fact, berate her at all. She would normally have offered to help Rose, but she was eight months pregnant, ungainly and awkward, and bending over did not come easily to her. When they’d gathered everything, they retreated inside the house—Rose at a walk, Patricia at a waddle.

Patricia did not say anything as they traversed the front drawing room and went into the back pantry. She didn’t speak until Rose had the shopping spread out in front of them.

“Rose,” Patricia said quietly, “have you considered going back to Papa?”

Rose had not. Her stomach clenched at the very thought. “How could I leave you, when Dr. Wells will not return from his tour of duty for more than a week yet? I promised him.”

Patricia’s husband was a naval physician. He’d bent sent to Sierra Leone around the time Patricia had realized she was with child, and Rose had come to attend her sister in his absence. But it wasn’t just her sister’s welfare that had Rose worried. Their parents lived in London—so close, and yet impossibly far from the Royal Observatory. At her father’s house, there would be no computations, no comets.

No Mr. Shaughnessy to set her nerves on edge.

“You know,” Patricia said, “you know that he is the most incredible rake.” She did not say who he was. She didn’t need to.

Rose set the oranges in a bowl, refusing to look at her sister. “He’s never once offered to seduce me. I don’t even think he’s thought of it.”

“He’s thought of it,” Patricia said dryly. “And frankly, Rose, the way he’s talking to you? I don’t think he’ll even need to offer.”

Rose let out a long breath and shut her eyes. It was, unfortunately, true. Mr. Shaughnessy was…well, he just was. His name had been on all the ladies’ lips since Rose was seventeen, when he’d earned renown—or infamy, depending on who was speaking—as the first man to write a column of advice for the Women’s Free Press, a radical paper that Rose should not have enjoyed nearly as much as she did. In the five years since his first column, he’d only built upon that reputation. He’d published four novels. His books were called “masterpieces of satire” by some, and “dangerous rubbish that was best burned unread” by others.

They had, by all accounts, sold well—and those who harrumphed about setting bonfires with them were the ones most likely to furtively purchase them in brown paper packaging.

Mooning after Mr. Stephen Shaughnessy was foolish. She knew how they looked, sketched to scale. Socially speaking, if he were an orange in Westminster, she was…an elderberry, somewhere in the vicinity of Tanzania.

“I love you, Rose.” Patricia sighed. “And I know you’ll make a good marriage, one as brilliant as mine. But you have to remember that most of the men who look at you won’t be seeing you. They won’t see that you’re clever and amusing.” Her sister came forward and took Rose’s hand in her own. “They’ll see this.” She rubbed the back of Rose’s hand. Dark skin pressed against dark skin. “It doesn’t matter how respectably you dress or how much you insist. Most men will see only that you’re black and they’ll think you’re available. So please take care, Rose. I don’t wish you hurt.”