But one couldn't deny that the survey had found some- thing, down in the southwest comer. And that something did look like a guard tower.

The three of us frowned at the computer screen until David joined us, took one look, rubbed his jaw, and offered another solution.

"Might be a vexillation fortress," he said.

Which was, I thought, entirely plausible. A vexillatio was a detachment of a legion, so a vexillation fortress didn't need to be as large as a full legionary fortress—it didn't need to hold as many buildings. I'd seen a vexillation fortress myself, at Clyro in Wales, that was roughly the size of our own site. And since they were only built as temporary campaign bases, they left very little evidence behind, much like a marching camp.

But Quinnell rejected that suggestion out of hand, refusing to admit the possibility. He wanted a site from the early second century, after all, and vexillation fortresses were remnants of the century before—the conquest years.

"No, no," he said, and tapped the screen again, accusingly. "A garden shed, or some old fence. That's what we'll find down there."

But as the week wore on, a careful expansion of the trial trench exposed clear evidence of post molds, and by the following Saturday Peter's optimism had evaporated. "A guard tower," he identified it, sadly. "It can be nothing else."

And marching camps, whatever else they had, did not have guard towers. Which meant that what we'd found could not have been the marching camp that sheltered the Ninth Legion on the eve of its last battle.

Peter sighed and poked the soil despondently with his trowel. "No, this really is the worst thing that could have happened."

It was the first time I had known Peter Quinnell to be wrong. Because the worst thing turned up half an hour later, on the end of his own trowel.

"The terrible part," I told Jeannie the next morning, as we sat together in the tiny, homely kitchen of Rose Cottage, "is that the head of David's department comes to lunch on Tuesday, the day after tomorrow, and Peter seems to have completely given up."

I'd never seen a man so unutterably depressed, so devoid of any interest in the goings-on around him. Since yesterday at noon I'd hardly seen him, and when I did he looked a shadow of his normal cheerful self, sitting wrapped in morose silence with one or both of the cats to comfort him, and his vodka bottle close at hand.

He didn't want company. And so, after breakfast, feeling utterly helpless, I'd come down to Rose Cottage and Jeannie.

She was a most relaxing woman. For all her energy and bubbly nature she seemed somehow to radiate an inner calm. Motherly, I thought, putting my finger on the quality. She was very motherly. Already she had filled my teacup twice and urged half a plate of her chocolate biscuits upon me.

"Aye, well, naturally he's disappointed," she said, stirring a second lump of sugar into her teacup and settling back. “It was coins that you found, was it?''

I nodded. ' "Three Roman asses—copper coins—from the reign of the Emperor Domitian. He was Emperor during Agricola's campaigns."

"And who was Agricola?"

"Oh, sorry. Governor of Britain, for a time. Agricola," I explained, “built forts and things all over Scotland, trying to push back the native tribes. Only then Domitian called him back to Rome, and the army withdrew again. They didn't really have enough men, anyway, to keep a proper occupying force up here. Our own fortress, or whatever it is, was probably abandoned within a year or so of AD 86—long before the disappearance of the Ninth."

"Why AD 86?"

"That's when the coins we found were minted."

Her expression was doubting. "But the coins could have been old when they were dropped here, couldn't they?"

"No." I shook my head, positive. "No, they were all three in splendid condition, unworn. And that kind of coin, once it's in circulation, tends to show wear very quickly. So they had to have been buried just a short time after they were struck. It gives us a very tight terminus post quern.”

“Oh, aye, that's just what I was thinking." Jeannie's mouth curved. "You're worse than Davy, you are, for explaining things."

"Sorry," I apologized, again. "It's just a term we use, for dating sites. In translation, it would mean the time after which something happened."

"Like, the Romans left after those coins were made?"

"That's right. We use a terminus post quern to help set a date range for the site, to say when it was occupied. Here at Rosehill, with the pottery we've found, and now these coins, we're looking at a rather tight date range of only a few years . .."

"Terminus pout quern," she murmured slowly, testing the sound of the words. "That's Latin, isn't it? D'ye ken Latin very well?"

"Well enough. It comes in handy, in my work."

"Aye." Her smile surprised me. "Robbie said you kent it. He was wanting to ask you what a word meant, I think, only yesterday wasn't the best day for it. I guess he decided to wait."

"He could always ask David," I said. "Archaeologists study Latin and Greek as a matter of course."

"Aye, so they do," agreed Jeannie. "But I think my son prefers your opinion to Davy's. You've prettier eyes."

Which was, I thought, a debatable fact, but I knew what she was saying. Robbie, like his collie dog, had rather taken to following me around while I did my work, and though the boy was much too young to have a true romantic crush on me, he evidently thought I was, as my father would say, “a bit of all right."