An exclamation from Hamilton arrested him.

"He's signalling," said the Houssa Captain, and Sanders put up his glasses again.

Bones's long arms were waving at ungainly angles as he semaphored his warning.

Hamilton opened his notebook and jotted down the message—

"Awfully sorry, dear old officer," he spelt, and grinned at the unnecessary exertion of this fine preliminary flourish, "but must keep you away. Bad outbreak of virulent smallpox——"

Sanders whistled, and pulled back the handle of the engine-room telegraph to "stop."

"My God!" said Hamilton through his teeth, for he had seen such an outbreak once, and knew something of its horrors. Whole districts had been devastated in a night. One tribe had been wiped out, and the rotting frames of their houses still showed amidst the tangle of elephant grass which had grown up through the ruins.

He wiped his forehead and read the message a little unsteadily, for his mind was on his sister—

"Had devil of fight, and lost twenty men, but got it under. Come and get me in three weeks. Had to stay here for fear careless devils spreading disease."

Sanders looked at Hamilton, and McMasters chuckled.