Excerpted from A Geography of Time by Robert Levine, ©1997:
The Chinese developed an incense clock. This wooden device consisted of a series of connected small same-sized boxes. Each box held a different fragrance of incense. By knowing the time it took for a box to burn its supply, and the order in which the scents burned, observers could recognize the time of day by the smell in the air.
If he hadn’t told already told you that it was the Chinese who invented an incense clock, I bet you would have guessed it. That just seems like the sort of thing they’d do.