Candle Clocks

“This method of telling time remained in use through at least the 18th century, despite the increasing ubiquity of traditional wound clocks. In addition to indicating the time, the candles could also serve as alarm clocks. One might stick metal nails into a candle at a desired time interval and place the candle in a metal holder. Once the wax melts at the desired level, the nail falls into the metal base with a clatter, serving as an alarm. This was another option for those seeking to wake up early: factory whistles, street criers, and (of course) roosters could also serve this purpose” (Madeleine Muzdakis, “Discover ‘Candle Clocks’: History’s Original Alarm Clocks before Electricity,” My Modern Met, July 12, 2021, https://mymodernmet.com/candle-clock-alarm/). You could recreate this with a tall candle and a nail. Light the candle before the teaching time starts and ensure that the nail is close enough to the flame that it will fall out as your teaching time is nearing the end. Make a special point to explain that using a candle made with a different combination of wax will change the burn time and the sounding of the nail alarm.