Ramage cursed to himself: he was far from sure that having reached a stalemate here with the Lynx, he should not sail and try to catch her consort. But would Tomás and Hart let him sail? On the whole it seemed unlikely, and the decision certainly rested with them. Suddenly to sail with the Calypso would panic the privateersmen, causing them to murder everyone, abandon their prizes and flee.

Abruptly he realized that the sentry was now rapping on the door of his cabin, a sure sign that previous calls had gone unheard. A shout from Ramage brought Orsini into the cabin to report that the survey and sounding parties were now ready and Mr Aitken had them paraded along the gangway.

Ramage wiped his pen, put the cap on the inkwell, stood up and reached for his hat. The difference between a young midshipman and a post captain, he thought sourly, is that the midshipman goes off on an expedition while the captain stays behind and scribbles . . .

He found three groups of men waiting for him. The largest, under the second lieutenant, Wagstaffe, comprised the surveyor Williams, both draughtsmen, the grey-haired botanist, Garret, and five Marines with Renwick.

His instructions were brief. The party was to land at the most suitable place, choosing somewhere they would use for the next few days. The boat would then anchor off, leaving a couple of seamen in it as boatkeepers. The survey would then start, continuing until there was not enough light, and without being too obvious Renwick would choose the sites for batteries. The posts with the plaques would be erected, claiming the island as British.

'It is most important,' he emphasized, 'that you all go about your business as though the privateer was not here. For the time being we have to pretend this is simply an anchorage for six ships. Don't do anything to spoil the impression I've given the privateersmen - that I will do nothing without orders from the Admiralty. So go ahead and measure your angles and distances. What will be your base?'

'I thought we'd erect a flagpole on the highest peak - or on a suitable platform which can be seen from all parts of the island.' David Williams said.

'Yes, but don't forget a signal platform will have to be manned eventually, and that means soldiers or seamen climbing up to it, perhaps in the dark.'

Williams nodded and admitted: 'Yes, sir, I'd forgotten that aspect. I was looking at it from a surveyor's point of view.'

Ramage turned to Renwick. 'You may find the camp on shore where the privateersmen are guarding the crews of their prizes. If so, give it a wide berth, but note its position and, without being too obvious about it, see how many men are on guard.'

'Details we'd need if we planned to rescue the prisoners,' Renwick said confidently.

'Exactly - but don't arouse the privateersmen's suspicions.'

With that he went on to the second survey party, led by Walter White and commanded by the Calypso's third lieutenant, Kenton. They had five Marines under Sergeant Ferris, but like Renwick's group they were dressed as seamen. Ramage was anxious not to alarm the privateersmen. Men dressed as seamen would arouse no curiosity but Marine jackets and crossbelts would. For the same reason the men were armed with cutlasses and pistols, not muskets. The pistols would not be very obvious; everyone knew that cutlasses were needed to cut a path through the waist-high brushwood covering much of the island.

With the second survey party following the first to shore, Ramage turned to the soundings team, commanded by Martin. They had, as instructed, all their equipment on the deck in front of them: two leads, the lines neatly coiled, an old butter firkin full of tallow, a boat compass, three notebooks, a quadrant and a telescope.

Ramage picked up one lead and inspected it, then the other. Each was a solid cylinder of lead, with an eye at one end to which the line was attached, and a depression cast in the other, to be filled with tallow.

Pointing at the firkin of tallow, Ramage said: 'Don't forget it's as important to know the type of bottom as the depth, so make sure you keep on inspecting what sticks to the tallow, and wiping it off before the next cast. Sand, small shell, broken coral, volcanic mud, silt... note it all down, and make sure you get your abbreviations right: don't rely on "s" - it could mean sand, silt or shell.

'Have you decided your base lines for triangulation?' He addressed the question to Martin, but was just as interested to see what Orsini had learned about chartmaking from Southwick in the last few hours.

'Yes, sir,' Martin said. 'Those two rocks that stand up like chimneys.' He pointed to one near the privateer, and a second one halfway along the peninsula forming the northern side of the bay.

Orsini said: "That first rock means we can keep on looking at the privateer, too.'

Ramage nodded. 'Yes, the number of men and the times they leave or board the Lynx. By the way, Martin, if you suspect there are isolated rocks, get a second boat so that you can sink a line between the two of you and sweep the bottom. Or anyway drag to a definite depth.'

'How deep, sir?'

'Five fathoms,' Ramage said. Few ships drawing thirty feet would ever anchor here; the phrase 'Swept to thirty feet' written on a chart was a warning that below five fathoms there might be isolated rocks to foul an anchor cable. It was all too common for a ship's cable to wind itself round rock or coral as she headed first one way and then another with each change of wind or tide, and often the first hint of trouble came only when trying to weigh - or the rock chafed through the rope and the ship found herself drifting, her cable cut and an anchor lost.

Turning to Rossi and Stafford, each of whom was now wearing a canvas apron to keep some of the water off them as they hauled up the lead, he said: 'You'll find Mr Martin will take you close to one or two of the prizes as you row a line of soundings. Tell him anything you notice - number of guns, how many guards, if any passengers are on deck, if sheets, braces or tacks have been unrove . . . you know the sort of thing.'

A few minutes later the boat was heading for the first rock, and through the telescope Ramage could see that she was being watched by the privateersmen. Once she was past the Lynx and the men started heaving the lead as the boat was rowed slowly across the bay, the privateersmen lost interest: the Calypso's boat was doing what their captain had said he had orders to do ...

Ramage snapped the telescope shut and said to Aitken: 'You have your shipwatchers at work?'

Aitken grinned and said: 'The privateersmen won't spot them if you can't see them, sir.'

Together they walked over to Bowen: the surgeon was wedged into the shadowy corner of a gunport, a slate on his knees.

'Not much to report, sir. There are at least eight guards. They had eight women walking the deck for half an hour, and then eight men - I presume the husbands; they were not dressed as seamen - for another half an hour. They used the after companionway.'

That was an important point: it meant that in the Earl of Dodsworth, one of the Honourable East India Company's newest ships, the sixteen passengers were almost certainly being kept prisoner in their own cabins. Eight married couples, eight cabins. Or were some of the women daughters with separate cabins? Or one or two of the men bachelors? It was a hopeless problem to work out. East Indiamen varied in the number of passengers they carried: there were different classes, the people ranging from important members of theCompany and its military service to clerks and writers, as they were called. Those big ships normally carried a couple of dozen passengers, the dozen most important paying a hundred pounds each (with food and linen extra) for the passage and the honour of dining at the captain's table.