Is "one" unnecessary in this quote of Melville?

I cannot make much sense of one in the following passage from Moby-Dick:

Now the various species of whales need some sort of popular comprehensive classification, if only an easy outline one for the present, hereafter to be filled in all its departments by subsequent laborers.

If outline is a noun in this passage, then one must serve here as a pronoun. If so, isn't the sentence lacking in punctuation? Rewriting would make it less ambiguous:

Now the various species of whales need some sort of popular comprehensive classification, if only an easy outline, one for the present hereafter to be filled in all its departments by subsequent laborers.

Furthermore, I can't help thinking that one is not needed here at all:

Now, the various species of whales need some sort of popular comprehensive classification, if only an easy outline for the present, hereafter to be filled in all its departments by subsequent laborers.

If Melville correctly worded this sentence, what is the function of one in it? What are your thoughts on my modifications?

I'll address one question here, the acceptability of the pronoun 'one' in

• Now the various species of whales need some sort of popular comprehensive classification, if only an easy outline one for the present, hereafter to be filled in all its departments by subsequent laborers.

Quirk, Greenbaum et al label this usage of the pronoun 'one' (they also mention others) as 'substitute one':

A Comprehensive Grammar of the English Language 6:55

The substitute pronoun one has the plural ones, and is used as a substitute for a count noun, or for an equivalent nominal expression:

• I'd like a drink, but just a small one.

Substitute one can be easily combined with determiners and modifiers:

• the old one in the kitchen

As Greybeard implies, the pronoun 'one' here sounds clumsy to modern ears. I'm not at all sure how or even whether this relates to particular antecedents. It seems rather to be related to the particular premodifier (which here must always be in an identifier, even if of a class [... I prefer to use a heavy one], not a descriptor, role).

• ??/*Today's high tide will be less dangerous than yesterday's one.

• *John's car is not as fast as my / Jill's one.

• ??/*_ A cricket ball costs more than a hockey one._

• ??/* the Cottage one on the kitchen table.

But

• _I prefer the new car / lawnmower / Jenny / design / operating

to the old one._

It appears that possessive determiners, possessive noun constructions, and attributive nouns don't readily accept substitution by 'one'.

This has been my own opinion on the matter; thanks to Araucaria I've been introduced to the work of Baker [See, for example, Corpus Linguistics and Linguistically Annotated Corpora By Sandra Kuebler, Heike Zinsmeister]. He claimed there was a grammaticality difference between the two sentences in

• (3) a. The student of chemistry was more thoroughly prepared than the one of physics. [example 14b in Baker 1978:415]
• b. The student with short hair is taller than the one with long hair. [example 23 in Baker 1978:419]

I wouldn't go so far as to say that (a) here is a representative of an ungrammatical category (and other researchers named in Araucaria's linked article come down heavily against this). But certainly Baker has picked up the fact that (b) sounds far more idiomatic, more natural, than (a), and that this is a general feature of adjectival vs attributive noun modification (whether post- or pre-) of substitute one. It also seems that acceptability of especially certain examples where conversion to adjetives (You have the chocolate eclair, and I'll have the coffee) is increasing quite quickly.

Other determiners, and adjectives (that, another, the previous / third, the red / light / tall / lowest / smelly / old / considerate / sophisticated / expensive / wooden / ...) all seem to work before 'one'. However, with some adjectives, it's more difficult to achieve sentences which sound natural ("I don't like Jim's three older sisters, but I'm fond of Sally ... you know, the considerate one").

The problem with Melville's sentence is that 'outline' is not an adjective but an attributive noun. Quite possibly, this usage sounded less unnatural in his day.

Here, one serves as a pronoun whose antecedent is classification.

Here’s a simple example:

• Which bag would you like?
• I’d like the blue one, please.

Adding a comma between the descriptor and the pronoun doesn’t maintain the sense and may make the whole sentence ungrammatical.

In my simple example, simply removing the word “one” doesn’t work either. In your quote, however, “outline” can be treated as a substantive, so “one” may be deleted as you suggest.

The intent of the original is a desire to have a classification, even one presented merely as an outline.

One is a pronoun, referring to the classification. It's the center of the noun clause “an easy outline one”, in which both easy and outline qualify one.

While older grammars classify one as a pronoun, modern grammars tend to classify it as an anaphoric common noun. This simplifies the rules around the usage of pronouns, because if one is classified as a pronoun, it's unusual in that it can have a modifier. However the meaning of one that is applicable here is listed under “One (pronoun)” in most dictionaries.

Here's what Melville is saying, broken down into shorter sentences:

1. Now the various species of whales need some sort of popular comprehensive classification.
2. For the present, the classification will be an outline classification, which is easy.
3. Hereafter, subsequent laborers must fill in the outline classification in all its departments.

The expression “outline classification” is a set phrase with a well-established technical usage. Contextually, it seems to mean a classification that is presented as an outline, that is, a hierarchical presentation of categories, their subcategories, their subsubcategories, etc., without significant details regarding the content of the (sub…)categories. (Programmers and computer scientists would call this a tree structure.) Here are some usage examples:

• (espistemology, ~1902) Charles Sanders Pierce's classification of the sciences. Pierce published several classifications of the sciences, some of which are termed “outline classification”. In his Principles of Philosophy, the part about the classification of the sciences starts with a chapter titled “An Outline Classification of the Sciences”, where he breaks down science into fields, then breaks down the fields into subfields, and so on, until he reaches categories that he described in one sentence at most. The net chapter “A Detailed Classification of the Sciences” goes into more detail about the process of classification. Here is a modern graphical presentation of this classification by Tommi Vehkavaara.
• (zoology, 1983) An Outline Classification of the Phylum Nematoda. Australian Journal of Zoology 31(2) 243–255.
• (botanics, 1982) “An outline classification of plants”, in An Introduction to Plant Taxonomy by Charles Jeffrey.
• (linguistics, 1992) “Outline Classification of the Indoeuropean Languages”, in An Indoeuropean Classification: A Lexicostatistical Experiment by Dyen et al.

It's somewhat uncommon to use a noun qualifier with one, but it can be done, especially when there's also an adjective. Here are examples that don't even have an adjective:

Although the planning system is the same regardless of whether a site is in an urban location or a countryside one, …
some people wrap that pig up in a pastry blanket, rather than a bacon one
Even though there are other types of showers (…), a tile one is a great option