I'd say you might want to determine literacy rates in the area and for the time period before ascribing any kind of meaning to what appear to be common mistakes. I suspect these kinds of reversed letters begin to decline with improved literacy rates, and also with the advent of the mortuary industry (and mass-produced, commercial headstones), which really got rolling around 1910. As a sort of rough measure, nearly 20% of the population was illiterate at the time the headstone was made, and a good percent above that would have been considered marginally literate. If the person wasn't in the business of producing headstones - which seems likely, given the time period - correct spelling wouldn’t have been a priority. 

https://nces.ed.gov/naal/lit_history.asp 

A quick spin through some of the Internet's finest information on reversed letters seems to suggest a lot of false paths, so tread carefully there. Not everything is a code that leads to secret treasure. 

Daniel B. Davis 
Administrative Branch Manager, Cultural Resources Section 
Kentucky Transportation Cabinet 
Division of Environmental Analysis 
200 Mero Street 
Frankfort, KY 40622 
(502) 564-7250 or (502) 782-5013
KYTC Archaeology and KYTC Cultural Historic

-----Original Message-----
From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of Pete Regan
Sent: Friday, February 24, 2017 7:12 AM
To: [log in to unmask]
Subject: Backward Lettering on Gravestone

Does anyone out there have information on the potential meaning of backward characters on gravestones? I have a crudely carved gravestone in a nineteenth century, family plot that was part of a central Maryland farm, with all of the D's, N's, J's, and 1's carved backward. Plenty of folks have suggested dyslexia or partial illiteracy as potential explanations, but I have a few archaeologist/historian colleagues who seem to recall that backward orthography can have specific meanings on gravestones. For what it's worth, here's the text as it appears on the stone (again, picture the aforementioned letters backward):

WM ONEAL
DIED.JAN
THE.1.1893
AGE.72.

The stone appears as the final photo in the larger site's state registration form, located here: https://mht.maryland.gov/secure/medusa/PDF/Howard/HO-1109.pdf

For some physical context, two adjacent stones (1906 and 1917) are professionally carved marble markers without any "incorrect" writing. The remainder of the graveyard consists of partial lines of unmodified, vertical slabs of fieldstones located west of the carved stones, presumably as markers for the graves of servants, the enslaved, or the poor. 

Any suggestions are greatly appreciated!