Don't say anything except to him.

We don't want any more excitement among the people than we can help." The Fourth nodded and went down the steps, and the Second began walking up and down the bridge, every now and then taking another squint ahead.
Again and again the mysterious shape crossed the disc of the sun, always vertically as though, whatever it might be, it was steering a direct course from the sun to the ship, its apparent rising and falling being due really to the dipping of her bows into the swells.
"Well, Mr.Charteris, what's the trouble ?" said the Skipper as he reached the bridge.

"Nothing wrong, I hope?
Have you sighted a derelict, or what?
Ay, what in hell's that!" His hands went up to his eyes and he stared for a few moments at the pale yellow oblate shape of the sun.
At this moment the _St.Louis'_ head dipped again, and the Captain saw something like a black line swiftly drawn across the sun from bottom to top.
"That's what I wanted to call your attention to, sir," said the Second in a low tone.

"I first noticed it crossing the sun as it rose through the mist.

I thought it was a spot of dirt on my glasses, but it has crossed the sun several times since then, and for some minutes seemed to remain dead in the middle of it.