Some Chinese clocks could tell the hour by smell
Chinese incense clocks measured time as a trail of incense burned at a steady rate. Different sections could use different scents, allowing successive hours to be marked by changes in smell.
How Chinese incense clocks told time by smell
Chinese incense clocks measured time as a trail of incense burned at a steady rate. Different sections could use different scents, allowing successive hours to be marked by changes in smell.