Some thoughts I want to share with the group before we move on. I have a couple excerpts from CM ch 2 that I think link together thematically. Following are my responses/insights.
Excerpt from CM ch 2
Though her voyage of twelve hundred miles extends from apple to orange, from clime to clime, yet, like any small ferry-boat, to right and left, at every landing, the huge Fidèle still receives additional passengers in exchange for those that disembark; so that, though always full of strangers, she continually, in some degree, adds to, or replaces them with strangers still more strange; like Rio Janeiro fountain, fed from the Cocovarde mountains, which is ever overflowing with strange waters, but never with the same strange particle in every part.
...
In short, a piebald parliament, an Anacharsis Cloots congress of all kinds of that multiform pilgrim species, man. As pine, beech, birch, ash, hackmatack, hemlock, spruce, bass-wood, maple, interweave their foliage in the natural wood, so these varieties of mortals blended their varieties of visage and garb. A Tartar-like picturesqueness; a sort of pagan abandonment and assurance. Here reigned the dashing and all-fusing spirit of the West, whose type is the Mississippi itself, which, uniting the streams of the most distant and opposite zones, pours them along, helter-skelter, in one cosmopolitan and confident tide.
First, I offer an image of the fountain illustrated in Vue de la Place du Palais, à Rio de Janeiro, a color plate found at NYPL from a book published about 1835. If you enlarge the image via the link provided, you may detect a social structure to the city-scape. Surrounding the fountain, we find a group of slaves, many of whom will spend their entire day transporting water from the fountain to their masters' homes. To the left, right, and front we find sailors who climb the stairways from the harbor beach to fill their casks at the fountain. A line of soldiers on the left faces the palace. A group of fashionable citizens stand about while government officials arrive or depart in their fancy carriages. Black slaves are found in every corner of the square.
In the extract above, Melville compares passengers to water particles. Even if we haven't visited Rio de Janeiro harbor, we understand the nature of cities and fountains, The water particles are distributed among all kinds of "pilgrims" travelling to the fountain in a continuous stream of mingled humans, white, brown, and black.
http://digitalcollections.nypl.org/items/510d47df-7b6d-a3d9-e040-e00a18064a99
This leads us to Melville's use of the term "piebald parliament." The fountain at the palace encircled by its patrons aptly fit this description. Note that the derogatory term "piebald" is a synonym for "motley", each expressive of the garb of a harlequin or fool. This matches as well the derogatory use of"Tartar-like" and "pagan abandonment" for this "cosmopolitan and confident tide".
At this point in the book, I imagine Melville wanted to work in "The River" fragment. If you re-read this fragment, consider that confluence of the Missouri and Mississippi may stand for the entrance to slave territory. Traveling southward from Galena, a riverboat passage enters Missouri territory on its starboard not long after it passes the rapids at Fort Madison Iowa, a few miles above Hannibal. The Missouri was entirely within slave territory from Kansas City to St. Louis.