"Stratograph" literally means "layer graph" and that's exactly what it is. Too slow for anyone to see, the Stratograph drops grains of sands down a clear tube. By accurately controlling the sand color and where the sand falls (using a pointed funnel) I can create relatively accurate pictures (see right, a self-portrait) in parts of the tube. In the rest of the tube, I use a motion sensor to pick which color to drop: the more motion the brighter the color. After months of running, what remains is a "core" recording the activity during Stratograph's stay.

So why create such a slow running machine?

I submitted a proposal for Stratograph for a traveling exhibit entitled "Playing With Time," which was to include 50 components, each of which address phenomena that are either too fast or slow for normal human perception, and opened in March, 2002. The exhibit was put together by the Science Museum of Minnesota and Redhill Studios, Sausalito. The museum was seeking a kinetic sculpture that might fit within the "Earth Changes" section of the exhibit--an area where examples of slowly formed natural materials (e.g. lake bottom and coral reef cores) are to be displayed.