To be specific, it’s the original contract between Harper&Brothers — one of the ancestor firms of current publisher HarperCollins — and Herman Melville for Moby-Dick.
Publishing contracts haven’t changed all that much since then; they’ve just gotten longer and more complex. Melville, wisely, had representation, in the person of his-brother-the-lawyer. (Literary agents in the modern sense — if Wikipedia is to be believed — didn’t become common until the 1880’s, and Moby-Dick was published in 1851.)
Dr. Doyle's Blog 
I still think that one of the study questions in the back of the Classic Comics edition (plug plug) should have been “Now do you understand why you should read the Bible and the complete works of Shakespeare?”
Thanks for posting this. I hadn’t seen the Harper post. I’m always interested in vintage contracts of this sort. Those years were tough times for authors, as evidenced by the short-term proceed sharing Melville was promised. It would have been extremely difficult for authors to live off the proceeds of writing, even multiple books, as Melville had. I’ll have to read it over carefully, and see what I can make of it.