3 ms·
I recall learning about this in high-school, which was in the Midwest in the early 1980's, so I don't know that it's as unknown in the U.S. as you say.
by rossdavidh 7y ago
I recall learning about this in high-school, which was in the Midwest in the early 1980's, so I don't know that it's as unknown in the U.S. as you say.
- deleted 7y ago[deleted]