Reproducing the writing often found in 19th-century letters 

I find the Esterbrook 314 Relief works well to reproduce the early 19th-century common writing with a quill. You see a lot of early letters where the letterforms are small, spread out, and written quickly. These are written with a quill. The 314 is pretty good at reproducing this look, and you can write quickly.
Around the early 1870’s a new style of penmanship, “Vertical Writing” came into vogue and was very popular into the first decade of the 20th-century. This is a style without shading, so is often written with a stiffer steel pen, like this Esterbrook 531 Flyer.