The design progression of the REMINGTON PORTABLES is so well covered elsewhere that we decided to give only the briefest coverage.  However, there is one oddball machine pictured last.

At left, a typical Remington portable, with what are called "flip-up" or "pop-up" type bars, operated by a lever on the side.  This is a No. 2.  These were good, solid well-made machines with such modern features as back-spacer, two-color ribbon selector and variable line spacing.  Margin set from back of carriage, and margin release operated by a lever on the carriage as well. 
From inception in 1920 through 1928 the Remington portables had the flip-up type bar design, which naturally was only employed to get the machine to be both workable but quite flat for encasement.  This extreme requirement for flatness was relaxed, apparently and in 1928 the Remington Portable No. 3 appeared.  This machine didn't have the flip-up type bars, and added margin release operated from the keyboard and a fixed-spacing tabulator as well.  Clearly a first response to such machines as the new four-bank Royal and Underwood portables.  The positive-acting geared type-bar mechanism remained, slightly modified.
As Remington certainly felt it necessary to compete directly with the larger, heavier portables from others it progressed to the No. 5 range, which was to be found eventually in a wild array of body styles and minor variations and names/models.  On the left, a 5T which is labeled as a MONARCH; below, a No. 5 in the much loved "streamline" or "deco" style body.  This streamlined body reappeared following the Second World War, but not for long.
We said there was one "oddball" machine to be shown and this is it.  This machine is a Remington No. 1 portable -- note the simple support for the type bars.  Its serial number is NV35224.

What is odd about it is that it has some kind of device built into the platen that we can't identify.  Look closely at the right end of the platen and you'll see a metal section just to the right of the rubber.  On that right, metallic section is a button with a spring under it.
On the right we see the right end of the platen, the metal section and the button (whose top is pointing right at the camera.)  Look at the platen -- there are three tangs, or hooks, which are visible in the rubber.  These pop up above the platen itself when the button is depressed.  Spring pressure returns the button, and the tangs, when the button is released.
Here, I'm holding the button down with a screwdriver and the tangs are popped out. 

The tangs point toward the typist.

They are not duplicated anywhere further down the platen.

They don't correspond exactly to numbers on the scale but are closer to actual inch measurements from the left.

The platen knob also has odd dots, spiraled around it partway.
We don't know what this thing is supposed to do.  If anyone has an idea, let us know.  One thing I DO know is that no other is pictured or mentioned anywhere. 

This is also indicative of why it's a good idea to go ahead and examine what APPEAR to be run-of-the-mill machines!
The big geared type-bar Remingtons aren't bad typewriters, but they're notable for one thing -- they are much SLOWER than average.