I was listening to the In Our Time episode on the measurement of time and the guests were talking about incense clocks, which were an East Asian thing.
Basically you take a stick of incense that burns at a known rate, put some marks on, burn it, and use the marks to measure the passage of time. Or in more elaborate ones like in the image above, you put bells on strings and hang them on the stick of incense, so that when the incense burns to a certain point, the bells drop down and chime. Or things along those lines.
Others involved a trail of incense powder, and you told the time by where the trail had burned, or in the case of ones like in the image above, by where the smoke was being emitted from. Wiki says some designs could burn for a month.
But by far the method I was most taken with was one where you connect multiple types of incense into a single stick or a line of powder, so that each hour (or whichever unit of time) has a particular smell. I find that totally delightful for some reason. A very, very charming premodern way of doing things. Imprecise, but charming.
