In the 20th century, there were two spaces after an end of sentence period. (I still do that.)
[1] https://en.m.wikipedia.org/wiki/Non-breaking_space (see specifically the example section)
Only if you used a typewriter. I was using (La)TeX in the twentieth (1990s), and it defaulted to a rough equivalent of 1.5 spaces (see \spacefactor).
Two ('full') space characters were added because of (tele)typewriters and their fixed width fonts, and this was generally not used in 'properly' published works with proportional typefaces; see CMoS:
* https://www.chicagomanualofstyle.org/qanda/data/faq/topics/O...
Bringhurst's The Elements of Typographic Style (§2.1.4) concurs:
* https://readings.design/PDF/the_elements_of_typographic_styl...
* https://webtypography.net/2.1.4
* https://en.wikipedia.org/wiki/The_Elements_of_Typographic_St...
In HN, you can force two spaces between
sentences. But only in code blocks.I could never agree with this, because monospace fonts are already adding extra space with the dot character, which is much narrower in proportional fonts. That fact alone makes the visual gap already similarly wide as it would be in typeset proportional text. Adding a second space makes it much too wide visually (almost three positions wide). It looks like badly typeset justified text.
(I understand why people are doing it, I just don’t agree on aesthetic grounds.)
I keep punctuating like it's the 18th Century, myself;—compound points are my favorites:—like the colon-dash compound, AKA the "dog's bollocks."
[1]https://en.m.wikipedia.org/wiki/Swastika
Which is to say, we all compromise.
I'd hate to lose my em- and en-dashes, but the original post seems to misuse en-dashes where hyphens belong (it could just be a font issue, but no matter).