Crammed into the barrel are hightech motion sensors that trace the movement of the pen, and smartphone-style electronics that give it enough computing power for a word recognition system.

He and colleagues applied these to measure the slow mixing vertical rates in the ocean, and to trace the movement of patches of surface water.

With this, they were shortly thereafter also able to trace the movement of electrons on the subatomic scale in real time.

In media art, one can trace a movement from artwork to network.

As regulators and police on three continents begin to investigate and trace the movement of the money, there was speculation that organised crime was involved in the missing millions.