From the same series as the previous post:

The stereo pair with contrast and detail restored:

The anaglyph (requires red-and-blue-stereo viewer):

During most of 1865, the year when this photograph was probably taken, Walt Whitman was back in Washington after spending the second half of 1864 in Brooklyn on sick leave. Still, he was in Brooklyn again on the April day when he and his mother read of the death of Abraham Lincoln. So it may just be historically possible that one of the men you see here on the deck of the ferry Pacific happens to be Walt, and Walt is asking you:

Who was to know what should come home to me?
Who knows but I am enjoying this?
Who knows, for all the distance, but I am as good as looking at you now, for all you cannot see me?