In article ,
Harlan Messinger wrote:

Every single place on-line that I can find that describes a slope ratio
defines it as the ratio of drop to horizontal distance (rise-to-run
ratio), and then gives an example of the exact opposite--for example, a
2:1 slope ratio is illustrated by a one foot rise for a two-foot run. Is
it that there was a mistake in one landscaping textbook 50 years ago
that got perpetuated, so that now everyone in the landscaping business
is confused?

That's as good a hypothesis as any. I know my landscaper is confused
about the topic, and consults me on every new job design. Something
about math eludes people.

Back in the stone age when I took a research class in college, the story
was told of a fairly prominent researcher who had sought at length in
vain for a particular statistic. It was the only piece of data lacking
in his otherwise complete paper. So, he made up a number. Fifty years
later, still considered a definitive authority on the subject matter,
his fictitious number was still being quoted by others.