Progress in developing a reliable pen was slow until the mid-19th century, due to an imperfect understanding of the role that air pressure plays in the operation of pens and because most inks were highly corrosive and full of sedimentary inclusions.
Progress in developing a reliable pen was slow until the mid-19th century that air pressure plays in the operation of pens and because most inks were highly corrosive and full of sedimentary inclusions. This was due to an imperfect understanding of the role.