This interesting machine was dropped off for basic service at Cincinnati's Urban Legend Institute (supporting WordPlay Cincy), where I volunteer as the Typewriter Guy.
I've occasionally seen these short-platen typewriters online, but have never before had a chance to inspect one closely. It turns out to be a complicated and mysterious device.
On the left end of the carriage we see not only a fairly conventional return lever, but a crank that moves the metal frame in front of the platen up and down. The frame is suited for holding a 4.5-inch-wide card.
The keyboard is unusual -- notice the numerals, which print the same whether shifted or unshifted.
Another remarkable keyboard feature is the "c/o" character:
The ribbon color selector is nonfunctional—it's unattached to any mechanism. Instead, the machine is designed so that when the card frame is all the way down, the ribbon is activated and the typewriter's shift is engaged. On all other lines, though, the shift is disengaged and the ribbon is out of commission.
The shaft can be removed when you pull on the knob to the right:
A narrow roller presses down onto the platen from above; there are no other feed rollers. In this photo, the narrow roller has been lifted up:
On the right end of the carriage is a knob that can be pulled to the right when you move the chromed retaining piece backwards. This pulls a shaft out from the platen, maybe allowing you to remove the platen -- but I couldn't actually find a way to do so, since the card frame gets in the way.
This video shows the machine in action. Note how with the initial turn of the crank on the left, the type basket goes down (shifting to capitals) and the ribbon goes up into printing position. The top of the card frame is just behind the printing point at this stage (in other words, it is serving as a platen). Returning the carriage advances the card carrier up by three spaces, returns the type basket into unshifted position, and puts the ribbon out of commission. You can then type another 5 lines.
So how was this typewriter supposed to be used?
Here are my inferences:
• The machine was used in a government office.
• It types 5 lines without the ribbon in order to create a stencil.
• These lines must have been an address; hence the "c/o" key.
• The top line (all-capitals, using a ribbon) may have been for typing an internal memo or label of sorts about a particular stenciled address.
• The roll is mysterious to me. Was it for making carbon copies of the stenciled addresses? Are you supposed to be able to remove the card frame somehow and use a roll for a separate purpose? In any case, the roll wouldn't be very big—there just isn't much room.
PS: Mystery solved!
In their comments, Phil and RobertG identified this typewriter as a device for cutting address stencils for the Elliott Stencil Machine, which was used for printing addresses on mail. See a similar L.C. Smith and the Elliott machine at 5:33 on this 1947 film.