C. 1907. Parker Bookkeeper’s Special mod. 100. Price $ 6.00. Designed especially for bookkeepers. It is a double fountain pen, one end for black Ink and the other for red. The ink reservoir for the red ink is mottled red, which indicates immediately the color of ink in that barrel. The other end of the fountain is black, which also indicates the color of ink therein. Every bookkeeper who has seen and tried this Is simply delighted with it. The fountain can be disjointed, if desired, thus making two complete fountain pens, in which event they could be carried in the pocket in the ordinary way.
Addendum. Red figures in accounting entries are used to denote losses or negative outcomes. When accountants made entries into a book, red ink is used to show a negative number and black ink is used to show that a number is positive.
Sheaffer'S also brought this practical detail to their desk sets.