In old English cursive handwriting why does the first s of two sometimes look like an f as in Congrefs or blefsings on page 1 of the US Constitution?

Answer 1

That goes way back to the Middle Ages. That first letter is called a "long s", less commonly referred to as an "extended s". It developed because it was easier to slide a quill pen from one letter to the next if you made it like that. When the printing press was invented it was so ingrained that people kept on using it for centuries even though it was not needed in printed material.

Michael Montagne