Charles,
The article in question may be "The Long Shadow of Winter", Sky and
Telescope Dec. '94, p.64. It turns out that the fellow who is kneeling
down and taking the observation is Anthony Cook, who I know. Tony is an
incredible Russell Porter fan and has uncovered more information about
him than anyone I know. He recently passed on an image of Porter's
conceptual SunClock for Griffith's Observatory (where Tony works), it's
absolutely enormous and employs a mirror (on top of the building) to
image the solar disk around an amphitheater where hour markers are
embedded, if anyone were to walk into the beams path they would have
been instantly vaporized! Anyone who is interested can contact me.
However, the shadow-sharpening reference was actually given to me by
Mark Gingrich, thanks again Mark! Also, it was Carl Trost (sp?), who
along with Mark, gave a superb talk on Sundials of the SF Bay area and
briefly introduced the idea to me on alignment to the limb, which was
apparently practiced by past artificers. This is how it all started
folks, would still like to hear more...
Regards,
Luke
[EMAIL PROTECTED] wrote:
>
> A couple of you asked about where I read of the shadow sharpener.
>
> I have the article, but it is packed away in storage. It would probably
> take several hours to find it.
>
> The best I can remember, it was in Sky & Telescope magazine (or possibly
> Astronomy magazine) in one of the issues between 1995 and 1997. The same
> magazine had an article about building a brass heliochronometer.
>
> I know that isn't much help, sorry. If I every find the article, I'll post
> the source.
>
> Charles
