"Wait a while. When the fog is so thick that you can't see Breakers P'int, then we start the fog-signal. That is the sign in that direction. On the other side of the lighthouse it is Jones's Neck that must be hidden. I guess both the P'int and the Neck will be covered this time. I must start the fire in the engine and have everything ready, at any rate. Let us go into the fog-signal tower."
Dave was delighted.
"I suppose, Mr. Tolman, people like to hear the signal?"
"Yes, if in a fog. They want to know which way to go. Even fishermen about here, who are supposed to know the way about the harbour, may be bothered by the fog; but people just off for pleasure may be bothered a good deal."
"See here! Isn't the fog lifting round Jones's Neck, Mr. Tolman?"
Dave was looking out of a window in the tower, and Mr. Tolman joined him.
"You are right; and Breakers P'int is clear too. We will hold on then, have everything ready, you know, for the fog may shut down suddenly."
Dave continued to look out of the window.
"Coming again!" he cried to the light-keeper, who had kept up his fires in the engine-room, but had gone for a few minutes to the kitchen. "Fog is round Breakers Point and Jones's Neck!"
Yes: like an immense gray sponge the mist had once more advanced, wiping out the vessels slowly sailing into harbour, the far outlying points of land, and now erased an islet called the Nub, mingling all in one confusing cloud.