(From
http://www.well.com/user/smalin/typinwhy.htm ...)
"The IBM Executive typewriter I found at a garage sale was magnificent, and (having been long since replaced by the Selectric), dirt cheap. Only somebody with a PhD in secretarial skills could operate it. It was a proportional spacing machine: an 'm' was five spaces wide, an 'i' was two. There were two separate space bars (two and three spaces respectively). To correct a mistake, you had to know the width of all the characters involved so that you could backspace the appropriate amount (backspace was the only single-space key on the machine). There was an arcane procedure for producing justified type which involved typing a page a first time (while using a special guide to measure where the lines ended), noting the extra spaces that needed to be added, marking the copy to show where two-width spaces would be replaced with three-width spaces (or, in the worst case, two two-width spaces), and typing the page a second time. Even loading the ribbon (it was one of the first carbon ribbon machines on the market) was a major challenge: its rimless reels would spill their contents at the slightest mishandling, and the thin (less than 1/2" wide) tape had to be threaded through bewildering series of slots, grooves, carriers, and guides. It was a machine only a fanatic could love, and I did. I made regular trips to Santa Barbara's IBM parts center, and spent hours with tweezers, probes, hooks, needle-nosed pliers and other fine tools, getting it working right."
Now, if some enterprising DUer wants to do the grunt work, it could be verified that the characters in the memoranda are FOUR distinct widths and the space are two distinct widths or a combination thereof.
It should be noted that the (semi-)proportional spaced type was
NOT a preferred office machine for filling out
forms! The military is and was rife with preprinted forms. It was almost only used for free-form correspondence and documents (posted announcements) where "eye-wash" was desired. Thus, it is not at all surprising that fixed-width typewriters were