Over the years, many accounts of the “Benjamin Franklin Milestones” suggest that Franklin used a measuring device (perhaps his own invention!) attached to his carriage’s wheel as the method for accurately placing the milestones. (see resource list below). My own measurements (with my car’s odometer) affirmed that praise of colonial precision. All found milestones (with the exception of IX) were each one mile apart.
However, I have not seen any evidence that Franklin himself did the measuring, marking, chiseling, or laying of the milestones. Given his responsibility for the entire colonial and early federal postal system, it would seem to be beyond the abilities of even a great man such as Franklin to personally conduct the installation of milestones along the post roads; the route from Woodbury to the county courthouse in Litchfield was not among the official post roads of early America, so Franklin’s participation in milestoning these roads is even more remote.
An appropriate vehicle to haul the milestones, stonecutting and stone-setting tools, and the worker(s) to lay the stones likely was more a working wagon than a gentleman’s carriage, perhaps akin to this 1906 photo of a U.S. Geological Survey horse-drawn wagon: