I recently came across this image in /r/ArtefactPorn and was wondering if anyone could explain why Boston and Charlestown are spelt Bofton and Charlfetown?
This refers to the "long s" of 18th century typeface. The "long s" was used when the letter "s" was used in the middle of the word as it is Boston and Charlestown. The "long s" dates back to Roman times and derives from the cursive depiction of the letter "s" in the middle of the word.
The "long s" was simply how people wrote the "s" sound when it was in the middle of the word. Its usage varied from place to place, but generally held to this rule. It eventually fell out of usage by the 1820s in favor of the regular "s" we know today. It did not affect pronunciation of the word, "Bofton" would be pronounced the same as "Boston."
Source:
They're not. What you see is a long s, which is pretty much how people wrote "s" from about 800 to the 19/20th c. From ca. 800 to ca. 1100, it was the only form of the "s" that most writers would use, with the now-standard short "s" slowly coming back first in the terminal position, and then slowly infiltrating into the word.