'Oh?'

'It's the paddles, d'you see,' Quier explained, his pleasant face betraying his enthusiasm. 'They function best at a particular draught; if the ship rolls heavily, the deeper paddle has greater effect than the shallower one. When steering a course the inequities tend to cancel each other out, but when manoeuvring, matters aren't so predictable.'

'I see. D'you use the sails to help?'

'You can, sir, but we don't usually have sufficient men to do all that if we are manoeuvring to lift a buoy.'

'No, of course not...'

'And when we set our sails to assist the steam engine, the steady heel, though more comfortable, tends to hold one paddle down all the time.'

'Yes,' Drinkwater nodded, 'yes, I comprehend that.'

'You see, it doesn't usually matter too much, sir, because we can only pick up buoys in reasonably good weather ...'

'Yes, of course,' Drinkwater broke in. Then, seeing Quier's crestfallen look at the interruption, he added, 'A long time ago, Mr Quier, I myself served in the buoy-yachts.'

Quier looked at his passenger in some astonishment. The old man's face was shadowed by the collar of his cloak and the forecock of his hat, but Quier could see that the watery grey eyes were shrewd, despite one curious drooping lid with what looked like a random tattoo mark upon it. The deeply lined mouth curved into a smile, revealing by a slight asymmetry that one at least of the furrows seaming Sir Nathaniel's cheeks was due not to the passage of time, but a sword-cut.

'You are surprised, I believe.'

'Only that I supposed you had always been a naval officer, sir.'

'I was unemployed after the American War.' Drinkwater saw the young man frown. 'Not the recent affair,' he explained, referring to the war which had ended twenty-eight years earlier and during which Mr Quier might just have been born, 'the first American War.' He paused again, adding, 'in which the United States gained its independence.'