The Sand Clock is an interactive metaphorical representation of time.

A grain of sand appears each second that passes in a day. The grains slowly fill the screen until midnight, when yesterday's sand vanishes and the cycle repeats anew.

The sand shifts as if blown by a gentle breeze, creating accumulations that erode and evolve over time.

You may shape these accumulations with your touch: the sand disperses softly beneath your finger.

The sand does not overlap or disappear -- it settles into vacant locations nearby.

Grains that appear in the morning range in color from shades of pale yellow through peach. During the afternoon and evening new grains appear shades of orange and beige.

Seconds that pass as a person is interacting with the clock appear in shades of red.

With 86400 seconds in a day, and slightly more possible pixel locations to fill, it is nearly impossible that the Sand Clock will ever appear exactly the same way twice.

Play a little, and be patient.... Be sure to allow the clock some time to evolve on its own and revisit it later to see what shapes have formed.

The basic artistic purpose of the Sand Clock is to encourage peaceful contemplation, develop concentration, and quiet the heart and mind.

Interaction with a Sand Clock is intended to be tranquil, meditative, and mesmerizing, direct, simple enough for a child, and rewarding, regardless as to a person's technical or cultural background.

At its most fundamental level, the intricate motion, pleasant responsiveness, and luminous color are designed to fascinate.

Discerning deeper, the metaphor of shifting sand recalls broad concepts of time and timelessness, life and loss, equilibrium, and nostalgia.

Its persistent evolution reminds us of the fluidity of the present moment, the impermanence of human touch, and the power of nature to reclaim.

The Sand Clock is a software application written in Java within the open source Processing development environment.

The logic it uses to govern the movement and interaction of the grains is subtly different for each of the five possible color ranges they may fall within.

Negotiating so many complex interactions is possible by bypassing computationally expensive graphics techniques and directly manipulating the pixels on the screen.

The physical installation consists of a PC, an LCD screen, a clear capacative touch sensor, and a simple electronic circuit.

The touch sensor lays flat over the LCD screen, and transmits touch data as x and y coordinates to the application running on the PC.

The circuit supplies the necessary voltages and ground, and other basic functionality.

The Sand Clock was inspired in part by prior examples of cellular automata and particle systems, and Mike Davis' Skyline project in particular.

It also bears some similarities with Conway's the "Game of Life", only in this case the pixels don't die; they remain on the screen to express the passage of time.