Thomas Jefferson said then and not than about his slaves

Recently, when I received a daily bulletin from delanceyplace.com, I was interested to see that Thomas Jefferson had used the word then where we nowadays would use the word than.

Here's the link to the particular article in the archive: http://www.delanceyplace.com/view_archives.php?2258

In a chilling assessment of the economic value of slave ownership, Jefferson said:

A child raised every 2. years is of more profit then the crop of the best laboring man.

I wondered if the word 'then' was a typo, so I looked around the internet and found what I take to be a reliable article, on the Smithsonian website. The article, The Dark Side of Thomas Jefferson, was a revelation to me about the disgusting practice of slavery. Whippings; selling of children 'down the river', never to be seen again; hypocrisy; brutal overseers doing the work Jefferson professed to detest - all these were part of a gripping article that I felt compelled to read to the end.

I've posted previously about the mixed history of these two spellings. I still think it's likely that in the future we will spell both words as 'then'.