Sundials were adopted in Rome during the early third century BC.
In the second century BC, Rome adopted water clocks – a container holding water with several holes at the bottom to allow the water to escape at a regulated rate.
The day was divided into ante meridiem (before midday) and post meridiem (after midday). We still use the abbreviations of am and pm today.
An hour was a variable thing.
Noon was the sixth hour.
3pm was the ninth hour.
The Roman Calendar
Before the reforms of Julius Caesar there is some debate as to whether the Romans followed a lunar, rather than a solar, calendar. Their year began in March and originally consisted of ten months.Two additional months, Januarius and Februarius were added in about 700 BC. After Februarius there was occasionally an additional month of Intercalaris.
In 46/45 BC Caesar implemented his new calendar. According to Suetonius:
He reformed the calendar, which the negligence of the pontiffs had long since so disordered, through their privilege of adding months or days at pleasure, that the harvest festivals did not come in summer nor those of the vintage in the autumn; and he adjusted the year to the sun’s course by making it consist of three hundred and sixty-five days, abolishing the intercalary month, and adding one day every fourth year. Furthermore, that the correct reckoning of seasons might begin with the next Kalends* of January, he inserted two other months between those of November and December; hence the year in which these arrangements were made was one of fifteen months, including the intercalary month, which belonged to that year according to the former custom.”
* In the Roman world the week-long festivals of Saturnalia (from December 17) and Kalends, (from January 1) were marked by decorating buildings with evergreens, exchanging gifts
This 15 month year was a one time correction.
January – Janus’s month. Janus is the god of gates and doorways, of beginnings and endings, depicted with faces looking in both directions.
February – Februa – Roman festival of purification
March – Mars, the Roman god of war. Originally the first month of the year.
April – Aphrodite’s month.
May – Maia’s month. Italic goddess of spring.
June – the month of Juno, queen of the Roman gods.
July – Originally the fifth month, Quintilis, when Caesar reformed the calendar he named this month after himself.
August – Originally the sixth month, Sextilis, when Augustus Caesar continued with the calendar reforms he named this month after himself.
September – Originally the seventh month
October – Originally the eighth month
November – Originally the ninth month
December – “decem” – ten – Originally the tenth month