First incense clock The incense clock, a type of combustion clock, is believed to have originated in China around 500 AD. Using this method, time is measured by burning punk (decayed wood or fungi) or incense (usually made of sandalwood and elm) at a slow and constant rate. As the material burns, it deposits ember along a path divided into sections representing specific times. The time is determined by noting the position of the ember. More elaborate versions of the basic incense clock had a weight attached to a piece of thread running through an incense stick. When the incense burned down far enough, the thread would be released and the weight would fall, clattering into a tray below. The noise would alert the owner that a certain amount of time had passed. Incense clocks were also used in India and were introduced to Japan from China. In Japan they have been used since the Nara period (AD 710–794) in the form of jokoban, a type of powdered incense burner used in Buddhist temples to keep track of the passing of time based on the length of a trail of ember deposited along an imprinted path. Read more about combustion clocks in the Clocktime article The first timekeepers: Telling time before the pendulum clock. Image Credits Chinese incense clock with one extra tray and maze, made by Ming Hsin, Chao, China. Chinese Incense Clock, Ming Hsin, Chao, China, Unknown Date, Mr. F. H Nash, Object number: 1952-184. Science Museum Group Collection © The Board of Trustees of the Science Museum, CC BY-NC-SA 4.0, https://collection.sciencemuseumgroup.org.uk/objects/co729/chinese-incense-clock-clock?_ga=2.11484669.857078137.1671705851-1843342385.1660747216 Fire Clock, Unknown, ID: ZAA0758 © National Maritime Museum, Greenwich, London, Foulkes Collection, CC BY-NC-ND 3.0, https://www.rmg.co.uk/collections/objects/rmgc-object-212049