I liked the point you made in Cavendish Experiment:Talk that Cavendish didn't determine G, only the density of the Earth. You were right. At first I thought it was just an issue of notation; since in their units G is (radius of Earth)^2/(mass of Earth) Cavendish and his peers determined the density of the Earth, but understood that it's real importance was in determining the strength of the gravitational constant. But now I am not sure. Your references seem to indicate that Cavendish never mentioned that aspect. Anyway you're right, the article should certainly be corrected to say he didn't determine the gravitational constant. In fact, I think the article could use a lot of improvement --Chetvorno 15:54, 31 July 2007 (UTC)
You asked about how to edit. If you want to edit the article, just sign in and click Edit. Here are some help pages that were useful to me: To learn the markup, Cheatsheet is a quick reference, How to edit a page has the details. For the correct style, Wikipedia:Guide to layout, and Manual of style is comprehensive. Wikipedia:Guide to writing better articles is essential Citing sources is important for scientific articles (well, all articles). And of course Five pillars. I try to stick closely to the existing article style, unless I'm doing a major rewrite.
One thing to remember about help pages: like everything else on Wikipedia, they are user-written. So they vary in quality and viewpoint, sometimes contradict each other, and often duplicate content. If you don't like one help page, you can often find another that covers the same material better. --Chetvorno 17:53, 31 July 2007 (UTC)