I am preparing to update a page on my web site which talks about a pet fantasy of mine: modifying the IBM Electronic Composer so that it could also accept typewriter elements, and even the elements for the Mag Card Executive (88 character elements for the proportional-spacing styles later seen on 96 character elements for the Electronic Typewriter Model 50).
Researching the subject once again brought me face to face with one particular issue that, of course, is obsolete in today's age of the laser printer, where mechanical restrictions have largely vanished.
And that issue is?
The IBM Executive typewriter was a conventional electric typewriter with typebars for the individual letters, except for one thing, the different characters could differ in width. Called "proportional spacing", this allowed typed material to look somewhat like professionally-printed typeset material.
The characters could be from 2 to 5 units in width, so the graduations in width were fairly coarse. This tended to be visible as a shortcoming in most typestyles (as the typefaces for typewriters were called by IBM), although some, like Text and Charter, seemed to hide it quite well.
In many typefaces, the letters m, M, and W were five units wide, while most capital letters, like B or E, were four units wide, and most small letters, like a or e, were three units wide. This was at least approximately proportional to the appropriate widths for those characters.
One of the early interchangeable element typewriters, a contemporary of the Blickensderfer, was the Hammond. The Hammond typewriter design served as the basis for the VariTyper, which many offices used to prepare forms, and which also was used for the round paper labels in the center of a phonograph record on many occasions.
The VariTyper had proportional spacing. It had a three-bank keyboard, which meant that there was one shift for capital letters, and another shift for numbers and special characters. Also, its touch was not the best; typing on it was slow and laborious, so it was reserved for special-purpose use. (This is why the Blickensderfer and all the other old interchangeable element typewriters died out after the Underwood Five became the gold standard for typewriters.)
Its characters were from 2 to 4 units. The standard spacing it used was very similar to the spacing the IBM Executive typewriter used for the Documentary typeface, one of the most popular, with a few exceptions. The letter r was 2 units wide instead of 3. And the letters m, M, and W were reduced to 4 units.
This didn't seem to compromise the visual appearance of text set with it too much, and so it seems to have set a precedent.
The unit system for the IBM Selectric Composer assigned widths from 3 to 9 units to the various characters. Comparing those widths to the number of units assigned to the characters of Times Roman on the Monotype, I found that in general there was a consistent ratio, except that the letters m, M, and W ought to have been 11 units wide instead of 9 on the Composer.
A single unit could be either 1/72", 1/84", or 1/96" on the Composer, and typefaces could be from 12 points to 7 points in height.
The IBM Mag Card Executive, and later IBM 96-character electronic typewriters and daisywheel typewriters, used proportionally-spaced typestyles which seemed to be only slightly smaller, in terms of the number of units they took, than Composer typefaces. Here, characters were between 3 and 7 units in width; characters with widths from 3 to 6 units on the Composer kept their width, while those 7 and 8 units wide on the Composer were one unit less wide on the proportionally-spaced typewriter.
So perhaps m, M, and W, which "should" have been 11 units on the Composer, would have been 9 or 10 units here, but they, too, received only the maximum width of 7 units.
And, thus, this history raises the question: up to a certain point, if mechanical restrictions impose a certain coarseness on the variety of widths used for characters, is making the widest characters narrower the lesser of the two evils compared to accepting a certain additional degree of coarseness?