Candle clocks are one of the ways that ancient people attempted to use natural phenomenon to keep accurate record of the time during the day. They consist of a long thin candle, which is marked at even intervals. When the candle is lit it burns down at a relatively steady pace, and by keeping track of which mark the flame is at, you can get a rough estimate of how much time has passed since it was lit.
As for the timer you can use any weight even coins.
You could even use incense and a ruler. Heck smokers do this all the time. A cigarette is about 5 min. 🙂