Father: I have mislaid my Fountain Pen
Daughter: I think mother found it.
Father: Why do you think so?
Daughter: She said that she had been washing her hands all day.

-Wisconsin’s Sheboygan Press, September 20th, 1911

Explanation for those who do not get the joke:
In 1911, when this joke was published, most fountain pens were the eyedropper type. They were filled with ink by removing the section and squirting ink into the barrel with a medial rubber bulb eye dropper. As the writer's hand warmed the pen's barrel while writing, ink would slowly seep through the section-barrel joint and stain the fingers. Quite a problem and a pain for people of the day. During this time, many pen makers like Rider, AA Waterman, and a host of others developed jointless pens or safety type pens. These were pens that had some special design so that the writers hand was not over the leaking joint.