'So this is another goddam false alarm,' said Campbell gloomily.

'Maybe not. I could be wrong. We can only find out by dredging.'*

3*

So we dredged.

As soon as he could Geordie had taken careful sightings of the reef. 'I'm going to nail this thing down once and for all,' he said. Then we'll cruise around it carefully and not too closely, keeping an eye on the depth, and take soundings and chart everything we can see. And then we'll decide what to do next.'

After we had satisfied him we got started. Geordie took Esmerelda in as close as he dared and the dredge went over the side. I could imagine it going down like a huge steel spider at the end of its line, dropping past the incredible cliffs of Minerva, plunging deeper and deeper into the abyss.

The operation was negative – there were no nodules at all.

I was unperturbed. 'I was expecting that. Let's go round and try the other side again.' So we skirted the shoal and tried again, with the same result – no nodules.

I thought that there probably had been nodules in the area, but the upthrust of our friendly reef had queered the pitch. We were all calling it Minerva by now, although Geordie and I were aware that it might be a different reef altogether – the seas hereabouts were notorious for vigias. I decided to try further out, away from the disturbance.

This time we began to find nodules again, coming in like sacks of potatoes. I was busy in the lab once more but becoming depressed. 'This is standard stuff,' I told my small audience. 'High manganese – low cobalt, just as before. And it's too deep for commercial dredging. But we'll do it thoroughly.' And day after day the dredging and the shifting of position went on, with the results of my assays continuing to be unfruitful.

Then one evening Geordie and I consulted with one another and decided to call it off. We had been out from Panama for over two weeks, nearly three, and I was anxious to carry on to Tahiti to be there before the Eastern Sun arrived. Geordie wasn't anxious over stores or even water -thanks to his careful planning we could stay at sea for up to six weeks if we needed to – but he felt that the activity, or lack of it, would begin to irk a crew which was after all partly made up of people to whom he'd virtually promised action and excitement. Campbell was quite ready to chuck the whole thing in -on a land search he would be more tenacious, but then he was seldom out there himself during the early exploratory days, usually only coming in at the kill, so to speak. And so we decided to call a halt to the proceedings and to turn towards Tahiti the next morning. The news was greeted with relief by everyone, the excitement of finding the reef we were searching for having palled. Campbell walked heavily across the deck towards the companionway, his shoulders stooped. I realized for the first time that he wasn't a young man.

'It's hit him hard,' I said.

'Aye,' said Geordie. 'What do we do now – after Papeete?'

'I've been thinking a lot about that. If it hadn't been for that damned diary then Minerva Reef would be the last place I'd go looking for high-cobalt nodules, but Mark's scribbling has hypnotized us.'

'We don't even know if he meant Minerva. Do you think he was on the wrong track?'

'I don't know what track he was on – that's the devil of it. I only leafed through those notebooks of his before they were stolen, and I couldn't absorb anything much in that time. But one thing did keep cropping up, and that was the question of vulcanism.'

'You mentioned that before,' said Geordie. 'Are you going to put me in the picture?'

'I think another little lecture is in order- and I'll deliver it to Campbell and Clare as well. It'll give him something else to think about. Get the three of you together in here after dinner, Geordie, and put a lad on watch, to keep Kane away. They'll be expecting a council of war anyway.'

And so later that same evening I faced my small class, with a physical map of the seabeds of the world unrolled on the charitable.

'You once asked me where manganese came from and I told you from the rivers, the rocks and from volcanic activity. And I've been doing a bit of serious thinking about the latter class. But to start with, the Pacific is full of nodules while the Atlantic hasn't many. Why?'

The professorial method, involving the class in the answers always works. 'You said it had something to do with sedimentation,' Geordie recalled.

That's the orthodox answer. It's not entirely wrong, because if the sedimentation rate is high then the nodules stop growing – they get covered up and lose contact with the seawater – the colloidal medium. The sedimentation rate in the Atlantic is pretty high due to the Amazon and Mississippi, but I don't think that's the entire explanation. I want to show you something.'

We all bent over the map.

'One fact about the Pacific stands out a mile; it's ringed with fire.' My pencil traced a line, beginning in South America. 'The Andes are volcanic, and so are the Rockies.' It hovered over the North American Pacific coast. 'Here's the San Andreas Fault, the cause of the San Francisco earthquake of 1908.' My hand moved in a great arc across the North Pacific. 'Active volcanoes are here, in the Aleutians and all over Japan. New Guinea is very volcanic and so are all the islands about there; here is Rabaul, a town surrounded by six cones -all active. There used to be five, but things stirred up a bit in 1937 and Vulcan Island built itself up into a major cone in twenty-four hours and with three hundred people killed.'

I swept my hand further south. 'New Zealand – volcanoes, geysers, hot springs – all the indications. South again to the Antarctic and you have Mount Erebus and Mount Terror, two bloody big volcanoes. And that completes the circle – a round trip of the Pacific.'

I turned my attention eastward. The Atlantic is pretty quiescent, volcanically speaking, except perhaps for the Icelandic area. There was the enormous Mount Pelee eruption down here in the Caribbean but as you can see that's only just off the Pacific ring – and Krakatoa is in it, over Java way. The only place you find nodules in any quantity is on the Blake Plateau – and the interesting thing about that is that the Plateau is exactly where the current runs from the Caribbean, which I've already mentioned as being volcanic.'

Geordie straightened up from the map.

'You've got a hell of a lot of places to choose from.'

That's the problem. And there are vents in the Pacific seabed which we don't know about – hell, we're almost on top of one now. But I know that high-cobalt area exists and I'll stake my reputation that we find it in a volcanic area.'

Campbell said, 'As I understand you correctly, the nodules in the Pacific, the ordinary ones which occur in the greatest number of places, have been slowly growing through millions of years as a result of long-ago volcanic activity. But you think there are places where certain nodules might grow faster due to specific and recent volcanic activity.'

That's it – and they'll be high-cobalt, high-nickel and so on because of the fast growth. The metals will be entrapped while they're still around, before they're dispersed into the general waters of the Pacific.'

'Urn. That still doesn't tell us where to look.'

'I want to stick around the Western Pacific,' I said intensely. There are plenty of known undersea vents here, and it's better fossicking round here than wasting our time.' I had other reasons, of course – I wanted to begin my investigation into my brother's death, but I was only too well aware that in Campbell's eyes the commercial venture was the main, perhaps the only reason for our carrying on. He had some personal stake but not necessarily enough.