Discusses some of the physical processes involved in the freezing of water. Traces the work of a variety of researchers who have discovered numerous variables involved in the complexities of ice. (TW)

Describes subjective-contour illusions and gives explanations for perception of shape and brightness in these figures. Supports cognitive mechanisms rather than psychological mechanisms. Gives examples of subjective-contour illusions and summarizes explanations of other psychologists with regard to this topic. (CW)

Discusses the acoustics of bells by examining what determines the quality of a bell, the frequency it emits, and the note perceived by the listener. The analysis concentrates on a ship's bell but also considers several handbells. Laboratory bench set up for studying bells and nodal lines of bells are illustrated. (BC)

Described is a way for an amateur to build a mercury-vapor ion laser which was devised by Dean Morelli. Morelli's laser emits bright pulses of green light and dimmer pulses of red-orange light and is the first gaseous-ion laser. (Author/DS)

Relates how Charles Martin Hall discovered the method of making pure aluminum metal in 1886. Retraces the events and steps that led to the process of aluminum purification. Includes diagrams of the apparatus used in the investigations. (ML)

Discusses the shock wave sweeping through traffic flow. Describes the characteristics of kinematic waves in different traffic flows. Presents the author's experiences in studying traffic flow. (YP)