Very few Roman hours lasted an hour
Like us, the Romans divided the day into 24 hours. But unlike us, their hours varied in length. For the Romans there were always 12 hours of daylight and 12 hours of darkness. Thus, for example, a daylight hour in high summer was considerably longer than one in midwinter. The first daylight hour (hora prima) began at sunrise, noon was the sixth hour (hora sexta), and the last hour (hora duodecima) ended at sunset. There were no minutes or seconds. Time jumped from hour to hour, as the day progressed. The busiest hours of the days were the fifth (hora quinta) and sixth hours (around noon), when most Roman men gathered in the forum to trade, catch up with the latest gossip or simply hang out with their friends. The night-hours were also divided into 4 watches or vigiliae (3 hours each): Prima vigilia, secunda vigilia, tertia vigilia, quarta vigilia. Other sources state that the night was divided into 8 watches: Vespera, Prima fax, Concubia and Intempesta (from sunset to midnight) & Inclinatio, Gallicinium, Conticinium & Diluculum (from midnight to sunrise). In summer months, as the days were longer than nights, so was the duration of the day-hour. It could be as long as (our) 90 minutes, during the peak of summer. Conversely, during midwinters, the day-hours were shorter — about 45 minutes — and the night-hours expanded to coincide with the duration of darkness. The Roman hours also varied according to the place when the Roman legions waged wars in far off lands, due to difference in latitude from the city of Rome. Understandably, the clocks that measured time during day, were solar clocks, as they relied on sunlight. They were simple sundials with a gnomon that cast a shadow on a graduated circular disc. And that’s how Romans told time, 3rd century BC onwards.