Let’s give it the test by taking out the “if” clause:
“Often I have lain thus, when the fact that I would actually freeze to death would come over me with such overpowering force as to break the icy spell . . .”
Something is missing. The “would” demands some setup, the condition—the “if”—under which White-Jacket would freeze to death: “if I laid much longer.” So we don’t need those commas. In fact, we reject those commas. But Melville apparently liked them. He must have had a comma shaker the size of a hogshead.
The second half of the sentence—“and starting to my feet, I would endeavour to go through the combined manual and pedal exercise to restore the circulation”—could have used a pair of commas to set off “starting to my feet.” The rule in such a construction is to use either two commas or none. If the sentence began with the phrase “Starting to my feet,” one comma would be perfect, but because it occurs in a compound sentence, following the conjunction “and,” there should be a comma on either side of it. You would never write, “And, I would endeavor to go through the combined manual and pedal exercise . . .”
“Often I have lain thus, when the fact that if I laid much longer I would actually freeze to death would come over me with such overpowering force as to break the icy spell, and, starting to my feet, I would endeavour to go through the combined manual and pedal exercise to restore the circulation.”
Not only are the commas around the participial phrase logical but they reinforce the meaning: the stop and start have the effect of sudden movement, ejecting White-Jacket from the sentence as from an ice-cube tray. You could do without the commas entirely:
“Often I have lain thus, when the fact that if I laid much longer I would actually freeze to death would come over me with such overpowering force as to break the icy spell, and starting to my feet I would endeavour to go through the combined manual and pedal exercise to restore the circulation.”
But that would give you a postmodern Melville. The comma is a jolt upright. It gives the narrator time to struggle to his feet. And the uncluttered version seems to drain some of Melville’s personality and leave a drier sentence, all juiced out. The commas add buoyancy.
Anyway, this rule that commas travel in pairs in introductory phrases following a conjunction is often broken. At The New Yorker, the official style is two commas or none, but many editors prefer the single comma and will break style when a sentence misreads. It’s a compromise. I am half inclined to give Melville this one, as in this instance his nineteenth-century punctuation falls within modern guidelines, and punctuate the sentence thus:
“Often I have lain thus, when the fact that if I laid much longer I would actually freeze to death would come over me with such overpowering force as to break the icy spell, and starting to my feet, I would endeavour to go through the combined manual and pedal exercise to restore the circulation.”
Melville has his tics, but he always puts his words in the right order. Once you fall under the spell of the writer, you look past those tics because you are more interested in what the writer says than in judging how well he grasped the editorial conventions of his time.
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