So I’m studying Roman archaeology, and while we’ve seen in class that Roman urban and rural planning & road systems generally followed clear N/S & E/O axes that they managed to survey and trace with some precision using nifty little tools (and from then, parallels, diagonals etc…) ; my teacher could not tell me exactly *how *they arrived at that primary N/S axis that then formed the basis for everything else.
I know they didn’t have compasses since those only arrived in the West circa the 13th century so… how did they do it ? General sort-of-thataway-ish reckoning by sun and stars ? Or did they have more specific tools or precise methods ?
They certainly knew where the pole star was, and how to find it in the sky, and they would have been perfectly capable of using and understanding both the shadow-based methods described at chacoguy’s link, so they probably used them, or variants of them, too. Greek and Roman astronomy and geometry were quite sophisticated. Heck, long before that, Babylonian astronomy was quite sophisticated.
The great pyramid at Giza is aligned to true N/S/E/W directions down to less than a tenth of a degree, so apparently the ability to tell true North accurately has been around for a while.
You mentioned “clear N/S & E/O axes” and then using a compass. These Roman structures you mention, are they aligned to compass North or true North? That would probably have an effect on the answer you are looking for.
Your question puzzles me quite a bit. There are a number of simple ways we can use to determine where the north is. It’s not at all mysterious. Why would you assume the Romans used different methods? It’s not like they were unfamiliar with the sundial or basic astronomy. To caricature a little (but not much, IMO), it’s a bit like if you were asking “How did the Romans figure out where the sun was rising?” I’m mystified by the question and wonder what kind of answer you could expect.
It’s not so much structures per se (we’re not there yet ), more stuff like the theoretical subdivision of the land around a new colony or captured city from an administrative standpoint, to be then distributed among veteran legionaries and the like. They basically (and, again, theoretically - in practice obviously the local geography influenced the process) traced a pair of central, orthogonal axes, often turned into big military roads; then used parallels to those axes to draw lots and lots of squares or rectangles of equal area. And from there, theoretically equal distribution of all arable land.
But whether they were aligned to compass north or true north… good question. I’ll try and ask
@engineer_comp_geek : thanks ! That’s exactly what I was looking for. Now to determine what “the stellar methods of the Egyptians” were :o
(found them here, if anyone’s interested. I’d actually learned about those back in school a loooong time ago and clean forgot about them)
It’s not so much that I assume the Romans used different methods than the article, but that the methods listed in the article rely on astronomical knowledge that may or may not have been wildly known in Roman times. And I have no personal notion of when those “simple facts” about the world became general knowledge.
To put it simply : it’s all well and good to say “oh, you just find Polaris, and there you are”. But in order for us to know that Polaris semi-accurately indicates due north, somebody, at some point, had to do all the calculations and observations and verifications and so forth. Was that work done in Roman times ? Was it during the 16th century ? Was it medieval Arab astronomers ? How the fuck would I know :o ? Same goes for “at noon, the shadow of a stick points due South”. It’s “simple”, but not exactly obvious or intuitive knowledge.
At the time the Great Pyramid was built, true North lay close to a much fainter star, Thuban in the constellation of the Dragon. The Romans derived much of their astronomical knowledge from the Egyptians, in particular the Ptolemaic theory of the universe. Egypt needed to measure time and the progress of the seasons accurately in order to predict the annual flood of the Nile, on which their economy was based.
Good point. It is on topic, because it indicates that the ability to align buildings N/S existed even before the Romans.
Yeah. I think a lot of people have a perception that “Ancient people were stoopid”. Sure, there was widespread ignorance and illiteracy, but that’s not the same thing at all to claiming that civilization was totally devoid of intelligent and educated people.
He mentioned “using a compass” only to point out that the Romans didn’t have compasses. So they could not possibly have aligned anything to compass north.
I am aware that, due to the precession of the equinoxes, Polaris was not the naked-eye star closest to true north when the Egyptians built the pyramids, but that was about as long before the Roman era as the Romans are before us. According to Wikipedia, Polaris has been “used for navigation” since “late antiquity” (which means the later part of the Roman era), even though it was not quite as close to true north as it is now (and it is still not perfectly coincident with true north, and, I think, never will be). Even before that, ancient navigators apparently knew that true north was in the region of of the constellation of Ursa Minor, between α Ursae Minoris (now known as Polaris, and now a little closer to true north now than it was then) and β Ursae Minoris, so they could (and, I have little doubt, did) find north by looking for these stars, of which Polaris is the brightest, and considerably the easiest to find (thanks to the ‘markers’ in Ursa Majoris). Finding north by eyeballing a point between Polaris and β Ursae Minoris would have been quite as accurate as all but the very most rigorous and careful applications of shadow-based methods, and simply using α Ursae Minoris (Polaris) as the marker for north would have been plenty good enough for most purposes, as they undoubtedly knew.
Ptolemy, of the Ptolemaic theory, did indeed live in Egypt, but he lived in the second century AD, well into the Roman era, and a good bit further away in time from the pyramid-building era than we are from him.
Babylonian, Egyptian, and, subsequently, Greek astronomers and geometers knew this stuff well before the Roman era. Finding north from shadows and the stars very likely goes back even further, to prehistoric times.
The builders of Stonehenge and other prehistoric monuments could not read or write, and knew nothing of the formal geometry and astronomical theory of the ancient civilizations, but they still knew how to align their buildings to astronomically defined directions, such as the solstices.
In my defense, I hardly think Ancient (or Medieval) people were stoopid. Truth be told, I don’t think the human animal or its operating system have changed very much since then.
But there is a distinction between stupidity and ignorance.
We’re not much smarter than Iulius Sixtus Paccus - we might even be dumber than him, if current events are any indication - but we do have a much larger body of accumulated and collated knowledge to draw from.
When the Ancient Greeks attributed thunder phenomena to bolts thrown by Zeus hisself, or when the Northmen credited them to sparks from Thor hammering at his celestial anvil, it’s not because they were 'tarded - quite the opposite, since obviously and self-demonstrably they sought to understand the world more, the better to be able to predict or influence it. Which is the opposite of stoopid.
That we now know that lightning is not related to the worldly influence of supernatural forces but rather the interaction of electro-magnetic fields and hydrostatic conditions has nothing to do with individual intelligence, and everything to do with the spread of education, i.e. dissemination of the deductions and inferences of really smart people over 20+ centuries.
Hence my reply to **clairobscur **: my question is not so much about the deduction process that led us to the various known ways any fuckwit with a stick can find true north in 5 minutes today, but *when *the roots of that deduction process happened. Again, it all seems bog standard, basic world facts to us today; so much so that even a *US Marine *can figure it out ;).
But I don’t know (or rather, didn’t before this thread) whether that specific kind of relatively narrow knowledge was readily available in 500 BCE.
Right. The insight you were lacking was that the Romans did not need to figure out from scratch themselves how to find North, the hard part having been done centuries earlier by others.
), more stuff like the theoretical subdivision of the land around a new colony or captured city from an administrative standpoint, to be then distributed among veteran legionaries and the like. They basically (and, again, theoretically - in practice obviously the local geography influenced the process) traced a pair of central, orthogonal axes, often turned into big military roads; then used parallels to those axes to draw lots and lots of squares or rectangles of equal area. And from there, theoretically equal distribution of all arable land.