How did the Romans measure time?

[Diocle]

As for the title, in which way the Romans measure dthe time? I mean for example during military operations, when they ordered to an unit to explore and return in a dermined lapse of time, or to set the time for the attack among very spaced reparts, or to fix a meeting time between rwparts or units ... the examples might be innumearble, but the question is the same how they did culculated the time passing?

I ask, because I'm writing a short novel on TWC (yes you've read well, I'm writing in english a story! I know: I'm a poor mad! thanks!), so I need to know if it is correct when you are describing a conversation set in the Late antiquity, talking of an exact perception of the time, so I searched in the Novels I've read, in many books but I didn't find a precise answer to the question: In the novels the problem is avoided with great care, in the military books isn't considered, in the historical works is threated (if it's threated) in a very vague way so, the question stand still: In which way could they be sure of the time passing by?

Clepsydra? Yes of course, but .... com'on how many had one?

Sundials? Yes, but , ....on the march?

The position of the Sun? Watching at the position of the sun can I tell you something like 'Soldier, come back here in three hours'? ... and if it's raining and you cannot see the position of the sun?

So, in the end, even if I might look like an idiot I decided to ask you FRATRES:

In which way the Romans measured the time in their everyday lives?

[Flavivs Aetivs]

We know they had water clocks that changed about every 2-4 hours, they were used for guard duty I think. Someone else can elaborate more though, I asked the same question on this forum earlier.

[Lyceum]

I asked this question to a lecturer a while ago and got a variety of stuff to look up, I'll try to remember and summarise, bearing in mind we want everyday stuff.

You basically have it right Diocle, all three being the major methods. It's worth pointing out that sundials were by nature stationary objects and communal (I think there are even a few jokes in Plautus and that late Roman comedian whose name I can't recall Quo something) so if you were in Roman territory you may well come across one.

Secondly there are certain natural hints in the day, sun rise and set, cock crows, dusk and you can quite happily work out the time from there based on the position of the sun and so on. Apparently this is quite a common and widespread human skill, and tribals can be reasonably accurate even now. Psychologists have also been working on the idea of internal "zeitgeibers" but while interesting, probably neither here nor there.

Also Romans rarely would be specific in their everyday lives so simply saying ok est nunc meridiem, ad cenam proficiscamur would be ok in many cases. I suppose in a military setting someone would call watch...

The Romans were well aware that longitude and latitude altered hours btw and actually how they defined horae changed depending on place and season. It sounds complex, it must not have been considered many similar systems still prevail all over the world. You basically have a decent amount of room in your description I guess.

BTW this stuff is why I've given up writing historical fiction, you can drive yourself mad. I still have a draft of a novel which stopped around ca. 200 pages because I couldn't accurately pin down a characters toilet habits in that situation and I'm waiting for more evidence...

[agrimensor]

i recently had a talk with friend about this, the romans did devide night and day each in 12 hours. so in summer the hours lasted longer as in winter. BTW several mobile sundials are found ( some even with corrections for several lat long). So in summer you can march 25 km in 5 hours but in winter it is an other story

[jvrjenivs]

As for the lovely enginering of water dials etc, do a search for Heron of Alexandria.

[M. Demetrius]

Until the advent and wide distribution of pocket watches, town clocks, etc., people had a less specific need for knowing when it was 04:34:33 AM than we think we do now. Moving around on foot mostly, people knew that timing was inexact.

Things happen. Bridges or trails wash out in rains. Saying "be back in three hours" would be less likely than "be back before dusk". It's not complex to determine about how much daylight is left in a given day, Easier on a sunny day, of course, but "dusk" comes earlier on a cloudy day, doesn't it? The relativistic nature of that sort of time measuring is pretty universal. For longer trips, it seems realistic to say, "I should be back in two or three days" than "I'll see you here at 3:15 tomorrow".

Water clocks work well, if nothing foreign falls into the pool. I don't think sand clocks (more accurate) were available then, because of the expense of glass, but I could be wrong on that. Water clocks probably wouldn't work well at sea, though, because of the motion of the vessel on the water. In winter on the limes in Germania, they wouldn't work at all unless they were kept in a specific, warmed enclosure.

Dawn, noon, dusk would be pretty easy to observe. Nights would be less exact. Yet soldiers on watch and the officers that controlled that must have had some way of judging the time fairly accurately.

[Nathan Ross]

I believe water clocks were most commonly used in courtrooms, to time the length of speeches (very important!), although they certainly appeared elsewhere too.

Dawn, noon, dusk would be pretty easy to observe. Nights would be less exact.

Quite true. But for those who are used to observing the night, it's perhaps just as easy to tell one period from another. Censorinus, in de die natali (3rd century) describes both day and night broken up into rough periods, each with a name and mainly determined by either the quality of the light or darkness or the behaviour of animals or people. The night is split into seven divisions, from vesperum (evening, before the rising of the evening star) to diluculum (daybreak).

Censorinus - 'The Birthday Book'

This method of approximately determining the time of night was probably quite common, if not so clearly delineated.

[Diocle]

So in a stroy you should avoid stuff like 'be back here in three hours' it is better to use expressions more vague concerning period of the day and of the night, ...well, well...well... Thanks!

Still one doubt: And on a more strict military field? .... the exact timing for the action was extremely important probably there was really someone with the fixed duty of measuring time ... they had passwords, espionage, secret operations ... well, in these matters, probably some form of watch was really used ...

[agrimensor]

As i already mentioned there where portable sundials. And The agrimensor or surveyor could give noon by sticking a stick in the ground and follow the shadow.
In battle they would wait until the oponent moved or the legaat gave orders to attack.
More importand was that they would hava had the sun in their back.

[Renatus]

It may be relevant to consider how, say, medieval armies conducted their operations before the introduction of reliable portable timepieces.

[Caratacus]

From the film "The Hallelujah Trail" - "When sun three hands high above horizon, we attack waggon train"! (If you've never seen this little gem - the attack took place in a sandstorm - quite hilarious.)

Mike Thomas

[M. Demetrius]

When you say, "well, in these matters, probably some form of watch was really used ..."

What do you mean by the word watch? Surely not a wrist-worn timepiece??

[john m roberts]

I've often wondered how the legions timed their guard reliefs. Because I know from hard, bitter experience, that there is no more infuriated creature on earth than a sentry whose relief is late in arriving. In my novels, I've had legions use a water clock. Of course, these don't work below freezing temperatures, so I had the guard relief clock situated next to a big watchfire in the center of the camp. But this is pure guesswork. Is there any authoritative information on this subject?

[Alanus]

I'm with John Roberts, We hear such expressions as "the seventh hour," ect. Maybe Romans didn't count right down to minutes and seconds, but they could record halfway into the seventh hour. In my novels, I use waterclocks.... also used by the Chinese. :-)

[petermac]

The earth rotates 15 degrees per hour, which is approximately the width of your hand held at arm's length. It's a simple way to approximate how many hours since sunrise or until sunset. It works just as well at night if you use a star or constellation on the ecliptic, or even the moon. The moon's apparent motion is slightly different, as it 'rises' about an hour later each night (I have wondered if this was the source of our concept of the 'hour').

Also of note is the Antikythera mechanism, an astronomical clock from the 1st century BC. Nothing as sophisticated as this was produced for 1500 years or more and as well as accurately calculating the positions of the sun, moon and planets, is thought to have been able to predict lunar and solar eclipses, as its gearing follows the 19 year 'saros' or eclipse cycle.

Cheers

Peter MacKinnon