Visualising present and past: a meter with a flexible pointer

Meters and gauges based on analogue pointers provide a convenient way to visualise single dimensional data streams, such as speed, voltage, altitude, or fuel level. However, often a small amount of historical information helps to understand the data at a glance, and reduces the need for constant vigilance; is the parameter relatively stable; is it increasing or decreasing? Have there been any transients in the past minute? What trends are present? This paper describes a virtual analogue meter with a flexible pointer that shows both the instantaneous value at the tip and bends to a brief interval of history along its length. The meter has been developed in the context of monitoring the electricity grid, but has many other potential applications.