The inventor of the Typen was Dr. Henry Emerson Wetherill (1871 - 1946) of Phoenixville, Pennsylvania. He patented his typewriter in 1926 under patent no.1,571,656, which refers to the Typen as a "Stamping Device". The patent was filed for in 1924 but Dr. Wetherill had a working example prior to then. We know that as a fact because the photo on this page of Dr. Wetherill using his Typen was syndicated in March of 1923. At the time the photo was taken, Wetherill mentioned that it took him 14 years to develop.
1924 - 1929
Dr. Wetherill's Specialties
Audubon, Pennsylvania, U.S.
This Typen is the kind of typewriter that one would expect to have been invented during the late 19th century alongside the Dollar or Childs, but it wasn't. Rather astonishingly it dates to 1924. Also, to call it a typewriter, by definition, may be a bit of a stretch. Though it can type on paper, it doesn't have a platen so it can type on most other surfaces, too. In that regard it reminds me of the Dart, which some could argue is actually a press and not a typewriter. Adding to the debate is what the inventor actually marketed the Typen as, a "Fountain Pen Typewriter" (get it?... Type-Pen), capable of marking, among other things, linen.
The Typen was sold by Dr. Wetherill's Specialties, a company that was most likely located wherever Dr. Wetherill lived at the time. The two ads I found placed the company in a pair of Pennsylvanian towns just 10 miles apart, Phoenixville and Audubon. I suspect that any and all production was at the hands of Dr. Wetherill himself.
With a small, 3" diameter and an advertised weight between 1oz. and all the way down to an unbelievable 1/2oz., the Typen would almost certainly had to have been very crude and almost toy-like in construction. At a retail price of $5 (which included a case and ink), the presumed value had to have been solely in the Typen's portability. In comparison, Simpex toy typewriters, which were better built but not as portable, were advertised at half the price of a Typen.
To operate the Typen, "The dial on its front and back is arranged with various devices to quickly locate, center and down the characters. The self-inker rotates easily upon special bearings and the glycerinized copying ink continually takes water from the air making one drop of ink write a day. The finger crotch can be bent to suit hands. Speed, alignment, and spacing are satisfactory." That "satisfactory" speed for the Typen was a paltry 17 words per minute.
First and foremost, Dr. Henry Emerson Wetherill was a surgeon by trade. He was also a bit of an expeditionist, mainly of the Arctic North, and a Free Quaker by birthright.
The chances of finding a Typen are slim but not improbable. The reason I can state this with a certain amount of optimism is because of a recent discovery of another of Dr. Wetherill's obscure inventions. The Trombone-Flute, a musical instrument of which there hadn't been any known examples, was abandoned in a basement for decades until it was discovered within the last few years. There may be a Typen currently suffering from the same abandonment issues just waiting to be pulled from obscurity.
In his latter years, however, Dr. Wetherill seemed to have taken to inventing some very novelty-esque products. For example I submit the I-Shade, which was some sort of ventilated eyewear, and also the Cizr.
On March 7, 1946, Dr. Wetherill died at his family home in Audubon. He never married and and never fathered any children. He died alone, found by a groundskeeper an estimated three days after he passed.