古罗马的计时系统

古罗马人建立了对现代时间概念产生深远影响的计时方法。1最初，罗马人将一天分为午前和午后两部分，但约公元前293年至290年间，他们从萨姆尼特人引入了希腊日晷，之后白天被进一步划分为12个小时。1公元前263年，又有一台日晷从西西里岛被引进罗马，而公元前164年，首个专为罗马城设计的日晷得以建造。1

由于受季节变化影响，罗马小时的长度并非恒定。1在地中海纬度处，冬至时一小时约为45分钟，而夏至时则约为75分钟。1罗马民事日（dies civilis）从午夜（media nox）运行到午夜，而自然日（dies naturalis）则从日出延伸到日落。1

罗马计时系统的遗产在现代语言和宗教实践中仍清晰可见。1英文术语"noon"源自罗马的第九小时（nōna），原本指下午三点，但约在1300年前后改为指正午。1此外，天主教会的日间规范时间——包括prime、terce、sext和none——均取名自罗马的计时系统。1a.m.和p.m.的使用方式同样继承自古罗马的时间划分传统。1

The ancient Romans developed a sophisticated approach to measuring time that fundamentally shaped how the Western world continues to track hours and structure the day. Around 293-290 BCE, Roman timekeepers adopted Greek sundials obtained from the Samnites, marking a turning point in their ability to divide daylight into measurable intervals 1. This innovation was followed by the introduction of another sundial from Sicily around 263 BCE, and eventually, in 164 BCE, the Romans constructed their first sundial specifically designed for the city of Rome itself 1.

The Roman timekeeping system operated on a principle quite different from modern fixed-hour divisions: the length of each hour varied with the season 1. At the winter solstice, an hour measured approximately 45 minutes, while at the summer solstice it stretched to about 75 minutes 1. The Romans recognized two distinct types of days—the civil day (dies civilis), which ran from midnight to midnight, and the natural day (dies naturalis), which extended from sunrise to sunset 1. This dual framework allowed them to coordinate both administrative timekeeping and natural observations simultaneously.

The influence of Roman timekeeping conventions persists in modern language and religious practice. The English word "noon" derives from the Roman ninth hour (nōna), which originally referred to 3 p.m. before shifting to its current midday meaning around 1300 CE 1. Additionally, the Catholic Church's canonical hours—prime, terce, sext, and none—take their names directly from the Roman timekeeping system 1. The legacy also survives in the designations a.m. and p.m., which continue to reflect the Roman division of the day into before and after midday 1.