“The square,” Ellen and Tom reply in unison. “Look, it’s still there, where you drew it,” Ellen adds.

“Did she smoke?” Tom asks. “Perhaps she’s dying for one.”

“No, wait. It’s not a cigarette packet,” Ellen says to him. “That would be oblong.”

“True,” I agree. “Bridget was quite particular about it being a square.”

The conversation revolves around square things for a moment or two—picture, house, window, field, two apple turnovers back-to-back—before Ellen turns to Tom. She learns about Florence, her cleverness and beauty, about the University of East Anglia, and about the emission of carbon dioxide into the atmosphere. “The coal in that range was laid down in the Jurassic era,” Tom is telling her when I leave the table to take Bailey out for his evening stroll. “We send it up the chimney and whoosh, we add Jurassic carbon dioxide to our present-day atmosphere. Carbon dioxide traps heat, which is good, otherwise we’d all be in the deep freeze. But with more and more CO2 up there from all the coal and oil, our nice warm blanket is going to get way too hot. We’re already at 330 parts per million, and . . .”

There doesn’t seem to be much sign of a heated atmosphere tonight. The sky is low, the air chilly, restless. I glance toward the kitchen and see Tom’s hand gesticulating, a pointed finger going around and around as he draws an unending circle. Then he makes a square and I hear them both laugh.

Of Ellen I can see only the side of her face. Her cheek, that is, and a portion of her neck visible through the slit in her high collar.

I imagine walking with her in mild dry winter sunshine, somewhere high. Returning at the day’s end, still talking, perhaps more freely in the twilight.

—

“How about a tramp to Beacon Hill?” I suggest as I help her into her coat. “While this weather holds? No Bailey,” I add, for the sake of the birds.

“It would be much too far for him,” says Tom admonishingly.

We agree on the day after tomorrow. “Thank you, both,” she says. “I feel quite restored.”

Her eyes are bright. She kisses us in turn, without any awkwardness. Her lips on my cheek are warm, fleeting. And then she’s gone, striding out to the road, the beam of her torch lighting the way ahead of her.

Neither Tom nor I say a word as we clear up. As he passes me a glass or a dish to wash, I catch his eye, but I can’t read his expression. When it’s all done, and I’m wiping the table, he clears his throat.

“Well. She listened to every word of my CO2 lecture. That’s never happened before.”

I carry on cleaning the table.

“She might just be crazy about atmospheric chemistry, of course,” he continues.