If two spaces is right and one space is wrong, why is it that I just opened up a half dozen books and saw that they only use single spaces? If two spaces is better for readability, why can't I find books using two spaces?
That's my point. Most books don't use monospaced fonts, which was the case given in the article for instances where you'd use two spaces. You don't often see monotype in emails you send, or word processors, or newspapers, or even (as pointed out earlier) in web pages.
If you're writing a technical manual, then you may want to use two spaces, but really isn't that something that would be handled by the printer?
I see monospace typefaces in email all the time. The fact you like your emails extra-infected does not mean I share your enthusiasm for HTML mucking up my monospace formatting when someone sends an email with source code in it.
I'm willing to bet that some back of the envelope calculation would show that the savings are not anywhere near that many pages, and that the pages saved by either reducing the font size or the measure of the lines would dwarf the savings from single spaces after periods.
I think it would be near that many pages, for many books around that size, at least. It depends in large part on how many sentences you fit on a page, after all.
Anyway, you're claiming a false dichotomy there. Standardizing on single spaces is an incredibly easy fix if you want to minimize space used up, and the space savings far outweigh the effort (regardless of the cost in readability). In fact, shrinking typefaces will damage readability more quickly than eliminating the second space between sentences -- so if you're going to shrink text, you might as well wipe out a bunch of spaces while you're at it.
It's silly to talk about whether shrinking margins would save more space than getting rid of "extra" spaces between sentences, when it's quite simple to get rid of the spaces whether you shrink the margins or not.
