‘I regret that they are unable to join me for some time, lord king,’ Cerialis said. Hadrian had been tempted to warn him, but had been relieved when the prefect had been adamant that his family stay away from Sarmizegethusa and wait until he received his posting as narrow stripe tribune to a legion, which must come soon. With any luck that ought to mean a decent sized base somewhere with a good house for them all. Hadrian had already requested that Cerialis be appointed to I Minervia when a post became vacant at the end of May and was gratified by the man’s delight when he told him of this.

After children and dogs, the king showed concern for the garrison’s horses and the welfare of the soldiers stationed at other spots in his kingdom. This went on for some time, before Longinus was invited to ask what he wished. His questions were equally banal, and when once or twice they approached a sensitive subject, the answers were vague and were not challenged. Hadrian had hoped to learn from the audience, but it did no more than confirm his impressions of both the king and of Longinus.

XV

Piroboridava

The Kalends of May

THE DAY BEGAN with excitement, Ephippus almost bouncing as he supervised the trial. This was the culmination of many long days of work since he had first rushed into the principia shouting, ‘I’ve worked it out, I’ve worked it out!’

Ferox had never seen the man so animated before, or indeed so ready to chatter. Sabinus and Dionysius had exchanged glances, while the nearby soldiers had adopted the wooden expressions that suggested they were trying not to laugh.

‘It’s a monâkon,’ the Syracusan had shouted so loud that his voice echoed round the courtyard. Heads appeared at several windows. ‘A monâkon! Just think of that.’

‘One-armed?’ Dionysius at least reassured Ferox that his guess was right. ‘I fear that I am still at a loss, my dear fellow.’

Ephippus regained some control as he realised that he was now the centre of attention and his nervousness tried to reassert itself. ‘My apologies. It is an engine. Philon of Byzantium writes of them, as do others, though no one for hundreds of years. I’ve never seen one, nor even a picture, but that is surely what it is. Thank you once again for the loan of Philon’s book.’

‘Did not even know I had it,’ Sabinus assured him. ‘Did you notice, sir?’

‘Geometry has always given me a headache,’ Ferox replied. He had read a fair few of the scrolls from Sabinus’ little library, but had struggled with anything talking about measures and ratios and set those aside. Thankfully it seemed that Ephippus had discovered something useful – or at least that was what he must hope, while he waited for the engineer to get to the point.

‘Geometry.’ The Syracusan was shaking his head. ‘Not geometry, my lord…’ He seemed genuinely puzzled to encounter someone so lacking in basic understanding and yet given a post of authority. ‘You must come and see!’ he shouted again and scurried away.