They stepped outside. The rain was so fine now that they could scarcely feel it. They made their way in silence across the muddy street, trying to dodge the thickest ooze and the widest puddles. Soon they were right up by the front of the locomotive, by the wide, splayed cowcatcher, and Collis looked up at the bright headlight as if it were the hypnotic eye of a huge Cyclopean monster.

They walked along beside the wheels, inhaling the smell of oil and steam, admiring the lavish giltwork and the shining brass. On the side of the cab was a scenic painting of Panama City, surrounded by cherubs and zephyrs and rosy clouds, as if it were a paradise on earth. The frames of the cab windows and the edging of the cab roof were picked out with gold Gothic patterns. Out of the rear window, his shirt-sleeved arms folded, a black cigar in his mouth, leaned the engineer.

‘How do you do?’ Collis called.

The engineer spat out into the night.

‘Maybe,’ Andrew said, after a lengthy silence, ‘if you had to spend your life in a locomotive cab in Panama, then you wouldn’t feel too happy about life, either.’

‘Maybe he doesn’t speak English,’ suggested Collis.

They walked a little further along the length of the train, past the mail cars, until they reached the passenger cars. These were far less lavishly decorated than the locomotive, although they were built of solid heart pine, and two of them had ladies’ apartments. Their seats were narrow and covered in plain broadcloth, but anything was better than the back of a mule. There were engraved-glass oil lamps burning at every seat.

After climbing up on the drop step and peering in at the windows, Collis and Andrew went slowly back to the Hotel Colón. Collis was feeling hungry now, and he could have done with a couple of thick chops and a tomato salad. Andrew took a couple of pinches of snuff, emitted two explosive bellows, and then blew his nose into his tobacco-stained handkerchief. The night was noisy with the rustle of rain on the rooftops, the gurgling of the sea by the harbour wall, the whirr of insects, and the ceaseless pssshhh-clank of the locomotive.

‘What would it take to build a railroad from San Francisco to St Louis?’ Collis asked.

Andrew folded away his handkerchief and looked at Collis sagely. ‘Millions of dollars, to kick off with.’

‘And what else?’

‘Expertise, I guess. Although expertise can always be rented.’

‘So where would we find millions of dollars?’

Andrew gave a northward sweep of his arm, encompassing the whole of the United States and its territories, somewhere out there in the rainy darkness. ‘There’s the government,’ he said. ‘They’re willing to finance a railroad if someone comes up with a route to run it over, and they’ll throw in more land than you could gallop across in a week.’