If you haven't figured it out yet, tap the screen to ripple. You can tap again while a ripple is already rippling; but two is the limit. If you try to make a third, the first flattens out abruptly. Sorry about that.
You can download Z'Ripple (9K Pilot PRC file). It's freeware, so you have no excuse not to, right?
Z'Ripple requires PalmOS 2.0 or later. It also requires MathLib, a freeware floating-point math library ported by Rick Huebner.
This is a programming exercise, and not likely to be revised. However, comments and bug reports are still welcome.
Z'Ripple is copyright 1998 by Andrew Plotkin. Please copy and distribute freely.