“I don’t know if that’s a coffee-boat going north; I can’t make out her hull against the land,” he said.  “Sometimes there’s a guarda-costa hanging round the point.”

“Better take no chances,” Adam replied, glancing at the Rio Negro’s funnel, from which a faint plume of vapor floated.

Mayne signed to the quartermaster in the pilot house and the bows swung round.  Half an hour afterwards, he rang his telegraph and the clang of engines died away while the throb of the propeller stopped.  In what seemed an unnatural silence, a few barefooted deck-hands began to move about, and one stood on the forecastle, where his dark figure cut against the shining sea.  The rest went aft with a line the other held, and when Mayne raised his hand there was a splash as the deep-sea lead plunged.  A man aft called the depth while he gathered up the line, and Mayne beckoned another, who climbed to a little platform outside the bridge and fastened a strap round his waist.

“We’re on the Santa Marta shelf, but I’m four miles off the course I set,” Mayne remarked.  “I want to work out the angle from the first bearing I got.”

Kit went with him into the chart-room, for he knew something about navigation.  They had taught him the principles of land-surveying at the agricultural college, and this had made his studies easier.  When he came back the moon was getting bright, but the haze had thickened on the low ground and the heights behind had faded to a vague, formless blur.  The trail of smoke had vanished, there was no wind, and the smooth swell broke against the bows with a monotonous dull roar as the Rio Negro went on.  She was alone on the heaving water and steaming slowly, but the noise of her progress carried far.  By and by a light twinkled ahead, leaped up into a steady glow that lasted for some minutes, and then went out.

“That’s a relief,” remarked Adam, who had struck a match and studied his watch.  “The ground’s clear and Don Hernando has somebody he can trust waiting at the lagoon.  You can let her go ahead, Captain.”

Mayne rang his telegraph and Kit went into the pilot house.  The dim light of the binnacle lamp touched the compass, but everything else was dark and the windows were down.  Kit could see the quartermaster’s dark form behind the wheel, and the silver shining of the sea.  There was a splash as the man on the platform released the whirling hand-lead.  When he called the depth Mayne gave an order and the quartermaster pulled round the wheel.  The swell was not so smooth now.  It ran in steep undulations and in one place to starboard a broad, foaming patch appeared between the rollers.  Kit knew the water was shoaling fast as the Rio Negro steamed across the inclined shelf.  It was risky work to take her in, because the fire had vanished and there were no marks to steer for.  Mayne must trust his compass and his rough calculations.

“Tide’s running flood,” he said to Adam.  “She’d have steered handier if we’d gone in against the ebb; but there’s a better chance of coming off if she touches ground.”