How we cite our quotes: (Chapter.Paragraph)
Quote #1
In summer, too…sitting here, one is often reminded of the sea. …the vastness and the lonesomeness are so oceanic, and the silence and sameness too, that the first peep of a strange house, rising beyond the trees, is for all the world like spying on the Barbary coast, an unknown sail. (1.18)
The narrator here (who is sort of Melville himself) compares sitting in his house in the mountains to sailing. Both are isolated and mysterious and exciting. Isolation here is kind of fun; it's a way to imagine an adventure story. You need to be cut off from civilization to have an adventure—though that cutting off can be done in imagination more easily than by actually going out on the ocean.
Quote #2
I saw, through the open window, a lonely girl, sewing at a lonely window. (1.41)
Melville says "lonely" twice, so you'll know that this person is lonely. It also perhaps suggests that the narrator is lonely too; Mariana is actually a figment of the narrator's imagination, so her loneliness is his loneliness. Lonely people think lonely thoughts about lonely people thinking lonely thoughts. With all those lonelies, it starts to look almost crowded in there.
Quote #3
Of a Sunday, Wall-street is deserted as Petra; and every night of every day it is an emptiness. (2.90)
Petra is an ancient Middle Eastern city. Wall Street is then empty and imposing. This is the case on Sundays and nights, when there is no business being conducted—but the suggestion, perhaps, is that Wall Street is always eerily echoey. Business is a lonely, abandoned endeavor.
Quote #4
But he seemed alone, absolutely alone in the universe. A bit of wreck in the mid-Atlantic. (2.137)
Again, Melville uses nautical metaphors to describe loneliness. Bartleby is a little clerk in an office, but he's compared to one of Melville's seafaring adventurers, lost at sea. This doesn't so much ennoble Bartleby as it makes him more ridiculous or pathetic; this is not a hero who is going to be out slaying whales.
Quote #5
And as for solitariness…the special curse, as one may call if, of the Encantadas…is, that to them, change never comes; neither the change of seasons nor of sorrows. (5.5)
The Galapagos are at the equator, so there's no change of season. That means it feels like time isn't really passing. Being alone is lonely, but being alone forever is more lonely than that even. Though maybe the turtles will keep you company.
Quote #6
Another feature in these isles is their emphatic uinhabitableness. It is deemed a fit type of all-forsaken overthrow, that the jackal should den in the wastes of weedy Babylon; but the Encantadas refuse to harbor even the outcasts of the beasts. (5.7)
For Melville, the Galapagos have no jackals, and are therefore uninhabitable. But today the islands are most famous because Darwin studied them—and what he studied there was diverse forms of life. Melville actually describes lots of different kinds of animal life; turtles, penguins, fish. "Uninhabitable" is a relative term; lots of things live on the Galapagos, if you're willing to see them.
Quote #7
The impression they give to the stranger pulling close up in his boat under their grim cliffs is, that surely he must be their first discoverer, such, for the most part, is the unimpaired…silence and solitude. (5.55)
Sailors feel like they must be the first discoverers, even if they aren't. Isolation is lonely and scary, but it's also kind of exciting; it can be easier to feel like you're important if you're alone.
Quote #8
At a secure retreat, an undiscoverable hiding-place, no spot in these days could have been better fitted. …surrounded by islands, whose inhospitable aspect might well drive away the chance navigator…the unmolested Buccaneers found here that tranquility which they fiercely denied to every civilized harbor in that part of the world. (5.85)
Again, isolation isn't such a bad thing when you're an antisocial criminal and pirate. If society is after you, it's better to be alone.
Quote #9
Those two unnamed events which befell Hunilla on this isle, let them abide between her and her God. In nature, as in law, it may be libelous to speak some truths. (5.147)
The suggestion here seems to be that Hunila first lost a baby, and then ships landed on the island at some point, and sailors abused or raped Hunilla. (See Characters: Hunilla) The isolation of the island, then, becomes the isolation of her trauma, or abuse. And while the sailors and the narrative rescues her from the first, they don't from the second. She remains isolated even when rescued in part because what happened to her is presented as unspeakable, and effectively as isolating her forever.
Quote #10
…for a long period the only companions of Oberlus were the crawling tortoises; and he seemed more than degraded to their level, having no desires for a time beyond theirs, unless it were for the stupor brought on by drunkenness. (5.180)
To be alone with the tortoises is seen as being the quintessence of loneliness. But really, aren't the tortoises the ones alone with Oberlus, rather than the other way around? He's way more likely to kill them than they are to hurt him.