There are plenty of apps that display the time - this one doesn't do anything else either. However, which other app conveys something of the fascination that has emanated from precision clocks equipped with a seconds pendulum for almost 200 years? For a long time, clocks whose pendulums performed exactly one half oscillation per second (and were thus about one meter long) were among the highlights of precision engineering and were the prerequisite for accurate time measurement in observatories