The shadow knows

Natural History, May, 2003

Neil deGrasse Tyson's article on low-tech science ["Stick-in-the-Mud Science," 3/03] reminded me of my career in educational television nearly half a century ago. Sputnik 1 had begun to orbit, and suddenly Americans noticed that their schools were not teaching much science. Auburn University decided to televise a class in science for the upper elementary grades; I was a physical chemist, but I could talk to kids, so they picked me. Because one bake sale could buy a couple of television sets for a school, I soon had thousands of students.

Besides doing four half-hour broadcasts a week, I made a lot of school visits. Among the simple experiments I carried in my purse was the "sun tracker," which included an empty thread spool, a straight pin, and a pencil stub with a bit of eraser remaining. To assemble it, you put the pencil stub into the hole of the spool and stuck the pin straight up in the middle of the eraser. All the class had to provide was a sheet of white paper and a window into which the sun shone at noon.

If you set the spool on the paper on the windowsill, and made a dot on the paper every day at noon where the shadow of the pinhead fell on the paper, you could plot a pretty good analemma in the course of a year.

Charlotte R. Ward
Auburn, Alabama

[PHI]

Two intriguing properties of phi ([phi]), the golden ratio, did not make it into Mario Livio's article "The Golden Number" [3/03]. Elementary algebra shows that subtracting one from phi yields its reciprocal (1/phi); and the fact that phi 1 is equal to the square of phi yields, by simple addition, the further fact that the sum of phi and its reciprocal is equal to two times phi.

It is small wonder that many of the ancient Greeks regarded geometry as a form of magic.

Maxwell Manes
Brooksville, Florida