The Clear Dome

A darkened laboratory room in Bristol at night, blinds drawn, dark green linoleum floor, the only light a bare bulb inside a low open wooden hutch at the far wall casting a warm pool, in the middle a small wheeled machine thirty-six centimetres long under a clear elongated acrylic dome with a slightly flared rim, beneath it a chassis of aluminium angle strips with screw heads, an orange-yellow coil, small relays and wires, at the front a vertical column with a black rubber ring topped by a cylindrical photocell with a ribbed hood turned toward the bulb, a small drive wheel under it, two narrow rear wheels on aluminium swing arms.