Posted by David Silber on July 4, 2021, 1:25 pm, in reply to "Early..........."
The Eagle Pencil Company made fillable pens way back in 1890s. It tickles me that they patented a cartridge filled pen in 1895 (sic!). The world had to wait another 55 years or so for the Waterman CF, though. IF you can open the photo, you'll see it.