Underwood 5
From Typewriter Wiki
The Underwood 5 is one of the premier "old typewriters". With over 5 million units built, it is statistically the most common typewriter to ever be built.
___History and Design___
Invented in 1895 by Franz X. Wagner, the Underwood 5 was the first commercially-successful machine to offer true "visible writing" -- the ability to see what you typed. Prior to the Underwood design, most typewriters were of upstrike design, with a rounded basket that printed on the bottom of their platens-- rendering the typed page invisible to the user.
