Many of us go through our daily time watching without knowing exactly what we’re saying when we’re asked, “What time is it?” and we answer, “7:45 am.”
If we are pressed for a meaning, we might say ‘am’ stands for after midnight. We’d be wrong. The abbreviation ‘am’ stands for ante meridiem which is Latin for before midday. The usual meaning I give to my kids for ‘pm’ is pre-midnight, which is also wrong. The abbreviation stands for post meridiem which translates to after midday.
But how do you record these abbreviations in your novel? Do you go with the simple am and pm? Or do you use the old fashioned way of writing them: a.m. and p.m.? Or do you use all capital letters: AM and PM?
Regardless of which method you use, the important thing is to be consistent. Pick one and use it throughout the novel.
The other option for writing time is the twenty-four hour clock. This makes 6:00 am into 06:00 hours, which is read as “O-six-hundred hours”. The O being the letter O, not zero. However, in some circles it is said as “zero-six-hundred hours”.
Using the 24-hour clock turns 6:00 pm into 18:00 h.
If you decide to use the 24-hour clock in your novel, I suggest doing research on its history to see if it fits. Unlike the ‘am’ and ‘pm’ system, the 24-hour clock hasn’t been used for as long as one might think.
Or more accurately, the 24-hour clock was used in ancient times when time was first being measured, but fell out of favour for the 12-hour system before the 1400s. This was due to Germany—who favoured the 12-hour system—becoming the main centre of clock making.
One of the earliest recorded return to the 24-hour system was in 1886 by the London Times, a newspaper in Canada. It was used by the Canadian Pacific Railway to keep the trains in sync with each other.
In 1893, Italy became the first country to initiate the 24-hour clock nationally. This is not a surprise considering they were one of the hold-out countries centuries beforehand that was slow to make the change from the 24-hours to the 12-hours system. Italy was followed by France (1912; French Army in 1909), Denmark (1916), Greece (1917) and Germany (1927). One-by-one, other countries in certain capacities adopted it too.
In 1915, with the First World War raging in Europe, the British Royal Navy made the switch to the 24-hour clock, and the British Army (1918), the Canadian armed forces (1917) and the US Navy (1920) followed suit. The US Army didn’t officially make the change until the Second World War, on July 1, 1942.
During the latter half of the 1900s, several organisations successfully made the transition to the 24-hour clock—US airlines Pan American World Airways Corporation, Western Airlines, British Rail—but in general, most organisations, companies and the general public use the 12-hour notation in North America.
The 24-hour clock is also referred to as Military Time because of its relationship with the military.
If your story is set in the past, check to see which system was used to ensure historical accuracy.