The nitrogen they got from condensed meat juices.
"This is very much more like what I expected," said Venning, looking from the broad river to the distant wooded banks, and from the dark forest to the blue sky.
"I can see two string of duck, a whole crowd of ibis on a little island, a crocodile and a hippo." Compton, who was facing the stern, glanced over his shoulder, then directed his gaze aft again.
"We seem to be traveling slowly," he growled.
"There's no hurry, is there ?" Compton raised his head a little, and looked under the shelter of a hand.
"They're coming," he said briefly.
"Eh ?" Venning stopped, and looked back.

The water glimmered under the sun like a vast silver sheet.

"I can see nothing." "Don't you see a dark smudge.

Well, that is the smoke from a steamer.

I thought at first it came from a land-fire.