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
