Thanks. I've long looked for such a resource.
Already have two similar books here, but online is quicker & easier to reference...
Hinton Rowan Helper's The Impending Crisis of the South: How to Meet It, which you have probably heard of. 1857.
Sort of the anti-Kettel. A southerner who hated slavery because it was detrimental to non-slaveowning whites, not because it was unjust to black people.
Tries to use the same batch of statistics to prove the great impediment that slavery produces, not its advantages.
I'm not enough of a statistician to tell who is right. Suspect both are, to some extent. Slavery was wildly profitable for some, and immensely destructive to the prospects of others.
http://docsouth.unc.edu/nc/helper/helper.html
Guy is amazingly long-winded and tends to over-egg his pudding. 400+ page book would probably have been much better edited down to <200.