1960s Typewriter Technology

To interpret the meaning of the dmr thesis, it is helpful to have an appreciation of what were the standards for mathematical typing in the 1960s.  For the most part, mathematical typewriting during this decade was a manual process.  You typed your thesis on a standalone machine, preferably a Selectric, or you hired a professional typist to type it for you.  Typewriters of this period did a poor job of supporting mathematical expressions… if you wanted to use a special symbol and didn’t have access to a Selectric, you hand-inserted it into your machine using a special stick called a Type-it.  If you wanted to type a subscript or superscript you needed to release the machine controls and adjust the platen by hand.

Brian Kernighan describes this situation in “UNIX – a History and a Memoir”, pg 99. –

“…It may be hard for readers today to appreciate just how labor-intensive it was to prepare documents before the creation of word processing programs, when there were only mechanical typewriters – better than clay tablets or quill pens, to be sure, but any change of more than a few words in a document would require a complete retype.  Thus most documents went through only one or two revisions, with handwritten changes on a manuscript that had to be laboriously retyped to make a clean copy.”

In 2010, mathoverflow.net launched a discussion asking people to describe what it was like to type a math thesis before LaTex.  Here is a link to the discussion board… and a sampling of the descriptions from that conversation…

“I typed my thesis in late Winter 1963, on an IBM Executive in the Bowdoin College Math Dept office after hours. This was before the Bouncing Ball (Selectric), but it had two or three removable type-bars at the side, and we had a couple of dozen special bars, each with its own character. If you wanted to type “αβαβ”, you’d have to remove the alpha-stick and attach the beta-stick. I think that there were relatively few characters I had to put in by hand: pp maybe, and certainly the inclusion symbols. It took me 45 minutes or so per page, and according to the rules at Harvard, there could be no corrections on any page (not even white-out).”

“I paid a secretary through the nose to type my thesis in 1964, doing much of it myself, and using carbon paper to get a copy. Lots of handwritten graphs of spectral sequences. The memory of that horrid process may be one reason I never published my thesis. It is roughly 150 pages of dense calculations.”

“My father was a mathematician, and, before the IBM Selectric typewriter, I can tell you that he bought an expensive manual German typewriter along with boxes of these plastic sticks, each with a metal head containing a math symbol. Very slow and very painful.”

“Later, department secretaries (there used to be more of them) would have IBM Selectric typewriters, which would use a metal coated plastic ball, and you would switch the ball to get different symbols. This normally worked pretty well, except sometimes the teeth on the bottom of the ball (which was serrated for some reason) would break. This would mess up the typing action, so it would no longer type the symbol or character properly.”

“I paid the technical typist in our department to type my PhD thesis on her IBM Selectric typewriter. After it was complete, I noticed that she had omitted an entire paragraph of one of the proofs in an early chapter. To correct this would have required her to retype a large chunk of the thesis, so I let it pass. During my defense, the external examiner remarked that this particular proof was a little terse…”

These quotes give a great sense of the barriers to efficient and effective math typing in the 1960s.
The summary we take is…

  • If you didn’t have a Selectric, typing math symbols was difficult.
  • Whether you had a Selectric or not, typing subscripts and superscripts was difficult.

Jerry Saltzer, inventor of Runoff (early text editor), describes with references to the Selectric operating instructions how a typist could actually work the machine to create sub-and-superscripts on the Selectric…

“With the Selectric typewriter, not only is the platen pin-feed, it seems to be driven by a gear and ratchet to maintain precise vertical alignment and interline spacing.  But there is also a lever, called the Line Finder on page 15 (PDF page 17), that can release the ratchet so that the operator can temporarily position the line up or down by hand. The Line Finder lever then can reengage the ratchet to realign the platen on the original line.

The Cardholder (on PDF page 16) provides both vertical and horizontal alignment lines.

It looks like the cardholder’s alignment lines, used in conjunction with the Line Finder, would allow a perfectionist with a good eye to do a good job of aligning sub- and superscripts.”

Selectric Parts Manual - Page 100
Line Finder - Page 17
Cardholder - Page 16

Contemporaneous Math Dissertations

MIT Six Lines Per Inch

We have looked through available collections of the best math dissertations from MIT and Dartmouth during the 1960s, to identify what were the typing standards from this period.  As expected, we found that a doctoral thesis would be double spaced using a six-per-inch line height, three typed lines per inch.  Most but not all dissertations were typed using 10 pitch, meaning ten monospaced characters per inch. 

Some dissertations were printed using 12 pitch, 12 monospaced characters per inch.  Dennis’s Harvard thesis was typed using 12 pitch.

The evidence from these pages shows a variety of spacing adjustments and slight rearrangements that is consistent with Jerry Saltzer’s description of customized positioning.  While there is a lot of variety across documents and we haven’t mastered the subject, there seems to be a general pattern with the PDFs we examined to show that subscripts and superscripts do not calibrate to line heights, they appear to be hand placed using manual adjustments.

MIT Examples of Sub & Superscript

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