nt time measuring devicesCandle ClocksIt consisted of six CANDLES made from 72 pennyweights of wax, each 12 inches (30 cm) high, and of uniform thickness, marked every inch (2.54 cm). As these candles burned for about four hours, each mark represented 20 minutes.Incense ClocksThey burned evenly and without a flame; therefore, they were more accurate and safer for indoor use.SundialsEvery day was divided into 12 equal segments regardless of the time of year; thus, hours were shorter in winter and longer in summer.HourglassIt was ONE of the few reliable methods of measuring time at sea, it is speculated that it was used on board ships as far back as the 11th century, when it would have complemented the magnetic compass as an aid to navigation.Clock TowersClock TOWERS in Western Europe in the Middle Ages were also sometimes striking clocks.Astronomical ClocksIt incorporated an escapement mechanism as well as the earliest known endless power-transmitting chain drive, which drove the ARMILLARY sphere.Wrist watchesWrist watches were first worn by military men towards the END of the nineteenth century, when the importance of synchronizing manoeuvres during war without potentially revealing the plan to the enemy through signalling was increasingly recognized.