How we cite our quotes: (Chapter.Paragraph)
Quote #4
His expression was concentrated, meditative, under the inspecting light of the lamp I held up to his face; such as a man thinking hard in solitude might wear. (1.43)
The captain might as well be describing himself when he talks about Leggatt's appearance. After all, the captain is the one who's been thinking in solitude a lot lately. And let's not forget that he constantly describes Leggatt as his "double."
Quote #5
It was, in the night, as though I had been faced by my own reflection in the depths of a somber and immense mirror. (1.53)
The captain comes really close to saying that Leggatt is imaginary when he says that looking at Leggatt is like looking in the mirror. Then again, it could be a coincidence that the two of them look the same. Or it could be the captain projecting all his own emotional baggage onto some guy who's wandered onto his boat.
Quote #6
It's clear that I meant business, because I was holding him by the throat still when they picked us up. He was black in the face. It was too much for them. (1.60)
There aren't many things that look worse than a man who's been strangled to death in the middle of a rainstorm. No wonder the sight of the guy was "too much" for Leggatt's crew.