>>12762411the archaic form of the S which was used up as recently as being written in the articles of confederation is called the long S, which is written as " ſ " which when handwritten looks closely to an " f " as there is also often a line on the left side, and used in all circumstances where an S would normally be except at the end of a word
ſ is also related to the german " ß, " or double S, where the curved line continues off of the original ſ
it is also possible that the line within the f could have it's origins in differentiating the ſ and f
