In old books, why the letter s is replaced with letter f, except the last letter of the word ?

by CeleritasLucis

I was reading the original pdf of a book published in early 1800s.

It's my first original source reading. It was very difficult to read, due to spelling change because of s. Also, last s is not replaced. And double s is also not replaced.

Was something wrong with this book ? Printer mistake ? Editing mistake ?

Here is the name of the book :

Historical Fragments of the Mogul Empire, of the Morattoes, and of the English Concerns in Indostan, from the Year M, DC, LIX [By R. Orme]. to Which Is Prefixed an Account of the Life of the Author  

TywinDeVillena

It is not replaced with "f". This is a problem that we have to face when dealing with OCR, as it will inevitably recognise the high s as an f. The "s" was written in two different ways in the olden days: the high s that can be mistaken for an f, and the low s, which is the s that we know today. This can be seen both in manuscripts and print books. Even today, in the Latin alphabet, there is one language that incorporates this two different esses: German. It has the letter ß , which is the union of the high s and the regular s.

https://en.wikipedia.org/wiki/%C3%9F

You'll eventually accustom to this type of duplicity