Assuming you’re not stuck in a prison cell without windows, you could feasibly keep track of the moon and tides by walking outside and jotting things down in your notebook. Alternatively, you could ...

The sun (HelioKron) and moon (LunaKron) clocks, on the other hand, are simpler and utilize the time and date. The HelioKron is equipped with a sound element that chimes an hour before sunset, a half ...