Spear (1993) is our first automatic tickler. It is an attempt to reproduce the unpredictable movements of a blade
of grass when it is blowing in the wind and gently touches your skin.
A spear of grass is suspended from a metal chain that runs through a circular contact. The spear is set into motion by a solenoid,
which in turn is activated by the movements of the chain. The device must be positioned at a fixed height above the body, so
that the tip of the grass strokes the skin lightly. This simple electro-mechanical system produces a chaotic oscillation,
resulting in unpredictable, jerky motion patterns.