There was a gentle tapping at the door. Quickly he slid off the bunk and turned the handle.

"Jackson, sir," a voice whispered.

"Come in, I'd given you up!"

A moment later the American was in the cabin, shutting the door silently behind him.

"Mr Yorke's awake in the other bunk."

"Evening, sir," the American said. "Is it-?"

"Don't worry," Ramage assured him. "Mr Yorke and I have just been talking about it. Have you-"

"Sorry, sir, I'm really reporting that I've got nothing interesting to report. Just one or two odd things..."

"Out with them!"

"Well, most of the men stay in the same ship. But although each packet makes three round voyages to Jamaica in a year at the most, some of the men change ships to get in an extra voyage."

"Why?" Ramage asked.

"Haven't been able to find out yet, sir; the chap I talked to was very mysterious. But I'll wager he makes a lot of money out of it."

"Ventures," Yorke whispered. "The more you venture, the more you gain!"

"Ventures!" Jackson repeated, clearly angry with himself. "That's what the fellow must have meant when he said he made the extra voyage because he liked the sunshine - 'it made the money grow'!"

Slowly the Lady Arabella worked her way to the north-east. The hour glass was turned regularly, the log was hove twice a day and the ship's speed noted along with the courses steered. Stevens made a great ritual of the noon sight - apparently he had turned it into something of a mystic rite which normally impressed the passengers. The Lady Arabella crossed the, invisible line of latitude at 23 degrees 27 minutes, marking the Tropic of Cancer, the northern boundary of the Tropics, and each day the temperature continued to drop slightly.

The drop was almost imperceptible; one night Ramage, accustomed to sleeping naked on his bunk to keep cool, wished he had a sheet to cover him; a couple of nights later he used it. Five days later he thought of a blanket, and the very next night pulled it over himself for an hour or so round three o'clock in the morning. That day the heavy canvas awning which had sheltered the after deck from the scorching sun of the Tropics was finally taken down, rolled up and stowed below.

The only thing that did not change was the diet: the food the passengers had provided for themselves was not very varied, since there had been little time to look around, and the packet's cook was neither skilled nor imaginative enough to do anything more than boil or roast whatever he was given. The fruit lasted well: limes and oranges were shrivelling but still yielding juice after two weeks; stalks of bananas cut at varying stages of greenness were ripening in succession.

Like the fruit, the chess contest was ripening. Playing against a tougher opponent had sharpened Bowen's skill; now Farrell had to fight hard for his increasingly rare victories. But more and more Bowen preferred to play against Southwick, with the result that Farrell was becoming remote. It was difficult to decide whether the passengers unconsciously edged him out of their circle or he withdrew of his own accord, but the reason was simple enough: he was an appallingly bad loser.

Each defeat at Bowen's hand led to Farrell holding an hour's inquest on the game: an hour spent describing and justifying, in almost excruciating detail, why he had made various moves. In the end, it seemed to Ramage, Farrell was always satisfied that he had proved he could only have lost because Bowen had been guilty of duplicity, if not of actually moving the pieces while Farrell was not looking.

The man's behaviour was inexplicable because Ramage could not credit that anyone could take a game of chess - or any game, for that matter - so seriously. He once commented to Yorke that if one got down to Farrell's level, the game became a business. Yorke pointed out that there Farrell had failed: from the beginning, despite cajoling and sneers, Bowen had refused to play for money. Farrell's disappointment had been obvious - at first, anyway, until Bowen found his stride and began to win more often than he drew or lost.

For Ramage much of the tedium of the voyage was removed because it gave him a chance of making a leisurely study of the personalities of several different men - Farrell, Captain Henry Wilson, Mr Much the Mate and his son Our Ned. Stevens was not worth much effort: he was a typical close man who, having made a little money, regarded the world with suspicion and divided it into two sections - the part which could make him further profit, and the part which might cost him money.

The sea, ships and seamanship had very little interest for Stevens, and far too much was left to the Mate. Stevens rarely seemed to reach any decision in the instinctive way of a true seaman: when he gave the order to reef, for instance, Ramage felt that he was applying some formula, or dredging his memory for a precedent. Yorke finally summed up Stevens: "He's a greedy man who long ago reckoned that owning and running a Post Office packet would make the most money in the shortest possible time. That's why he's not running a lead mine or a rope walk in Bridport."

The Mate's son, Our Ned, was the type of young man that, if he was serving in a ship commanded by Ramage, would have been transferred at the first opportunity. He was small and slim; his face was long and narrow with the eyes close together, two small brown buttons which had a tendency to glance uneasily from side to side. Perhaps it was just the shape of his mouth, but to Ramage he always seemed to be smirking secretly when he spoke to anyone: as though he was the possessor of some secret, or the speaker was being laughed at by people standing behind him. But for all that, he was probably the most useful man in the packet's crew. He knew nearly as much as his father - whom he treated alternately with patient affection and near-mutinous derision.

The Mate was a lonely man who lived in a private world; a world limited to the hull, sails, masts and spars of the Lady Arabella and occasionally lit by Our Ned. It was hard to define the Captain's attitude towards him - at various times Ramage had seen signs of irritation, awe, fear and respect. The Mate's attitude towards Captain Stevens was harder to discover because he spoke rarely, but both Ramage and Yorke agreed that it was based on contempt. It was as though Stevens had some guilty secret which the Mate knew about, disapproved of, but could do nothing to change.

Just as the Mate's world was the ship, Captain Wilson's world was the Army and, Ramage thought, at times just the barrack square. During every waking moment Wilson's life was drill and manoeuvre: his every remark was littered with military expressions. For Wilson nothing turned, it wheeled; nothing was passed, it was outflanked. Distance was range; going on deck for fresh air was making a sortie. Yet the blond-moustached captain had a clear if limited brain, even though he tended to see problems with the same deceptive clarity as the instructions in a drill book: if the enemy is behind that hill, you outflank him by this manoeuvre.

Once clear of the Tropics, the Lady Arabella ran into ten days of light, variable winds in which the packet tacked and wore two or three times an hour in order to steer not just in the direction they wanted to go but to avoid heading back towards the Bahamas.

After the variables came a gale and a sudden drop in temperature. It lasted five days, and the five passengers spent most of the time in the saloon playing cards or chess, or else lying in their bunks reading, wedged in by pillows and cushions against the rolling of the ship that tried to pitch them out.

On the afternoon of the last day, as the cloud began to break up and the wind to lessen, Yorke tossed aside the book he was reading and sat up in his bunk.