This would have been a very exciting mark to find! I love these old chiseled marks, especially when they're surrounded by chiseled letters like "USC&GS" and the date. We found one (XX) just a few yards away at the Northampton County Juvenile Detention Center, but "H," on the courthouse, eluded us.
To quote ArtMan in his Geocaching.com log for this mark, "You would need to use a ladder or be more acrobatic than I was willing to be to access this location." The window sill in question is easy to identify, but there is really no way to reach it or even get a clear view of the top. From the front portico of the courthouse Rich was able to obtain a reasonably good view of the top of the sill, but from that distance and due to the fact that the sill has been thickly painted over (probably several times), no chiseled marks were evident.