I may have a line on where Mr. Issac is buried.
My neighbor showed me a small forgotten cemetery in the lot next to ours.
The inscription on the main headstone reads:
"Richard W. Issac
July 21st 1855
59 years 7 months and 15 days"
Judging by your information, this appears to be the same Richard W. Issac.
The coordinates for the cemetery are
Latitude 38°58'47.33"N
Longitude 76°45'37.70"W
What more do you know about Mr. Issac. Would be nice to know who my neighbor is.