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How Ancient Mechanics Thought About Machines
friedo writes "The NYTimes has an interesting piece about Prof. Mark Schiefsky, a Harvard classicist with an interest in the history of science. Schiefsky pores over ancient texts in Greek, Latin, and Arabic to decipher the origin of knowledge that's been taken for granted for millennia. For example, a Greek treatise published a generation before Archimedes' proofs of the lever laws explains why, if you were a galley slave, you'd want to work the oars near the center of the ship instead of closer to the hull."
Being in the center has other benifits as well. You get the first chance at the gruel, you have one side of your body not being crushed up against the other galley slaves, all sorts of goodness. And one downside as well though. You're closer to the overseer's whip. So, I guess it evens out.
That which is done from love exists beyond good and evil
Ah, but maybe you were an educated person taken as a prisoner of war and enslaved. Perhaps you'd already read the treatise, perhaps whilst helping prepare for said war. Then, you see, you could politely ask your overseer to let you work the inside of the oars. Being suitably impressed with your grasp of physics, they would undoubtedly let you do so.
The problem is, you would rapidly figure out that you were badly mistaken in your choice. Working the inside oar gives mechanical advantage, sure, but what does that mean? You trade distance for effort. You are literally running back and forth while the guy near the edge barely moves.
This is well documented in later times when countries actually used galley slaves instead of free citizens like the Greeks used. The Greek oarsmen worked one to an oar, and each had to be well trained and motivated to work together efficiently. All the rowing positions in Greek galleys were nearly equidistant from the fulcrum. The oars in larger Greek galleys were arranged in banks, one above the other. In Roman or Turkish galleys, oars were manned by groups of slaves, and in this case the outermost position was the most desirable as it required the least movement and effort. In Greek galleys, the most desirable position was on the uppermost bank of oars because you didn't have your face pressed into the ass of the guy above you.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
http://graymonk.mu.nu/archives/2007/01/roman_navy_on_t.html
http://graymonk.mu.nu/archives/2007/01/superb_models.html
Look at the oars in all three cases. They are almost exactly the same length throughout each ship.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Only a tiny, tiny fraction of the books and scrolls within the Library of Alexandria survived, and who knows what kind of complex science and engineering was put into those books. The day it burned the world lost the greatest knowledge resource at the time.
Ever wonder how much knowledge was lost when the ancient Chinese burned all their books? http://en.wikipedia.org/wiki/To_burn_the_classics_and_to_bury_the_scholars
I often don't like the choices people make, but I like the fact that people make choices. That's why I'm a conservative.
It's documented that the missionaries actively destroyed Mayan literature as being pagan works of the devil. The small scraps left hint at materials that might have touched on everything from law to stellar cartography.
Literacy rates in the fourth century aren't known, but for Athens itself, at least, the literacy rates might have been very high. There is a lot of controversy on this subject. We do know that a number of dramatic works intended for public production introduced characters about whom a point was made that they could not read, but we aren't sure if their illiteracy was intended as comic relief (if illiteracy was unusual) or just a marker of class or status (if illiteracy was common). Keep in mind that the Athenians kept a lot of written monuments (stelai and the like) - there would be no point to them if literacy rates were *very* poor. However, I'm pretty sure there were NO borrowing libraries: what libraries there were tended to be private. Alexandria is the exception - but even it was most certainly not a circulating library, and it's later than this treatise.
The optimal product of force through distance ultimately depends upon build (body type). Most likely the lanky rowers will be positioned at the long end of the level arm, while the stocky people are positioned with shorter lever arms.
Since you probably aren't being fed enough, your primary risk is starvation through overwork. It wouldn't surprise me that rations were set low enough that many rowers had short careers, once they burned out their physical reserves. That was certainly the implication in Ben Hur.
Since you have to maintain cadence with the rest of the oars, your option to cheat is to catch late and release early. You can bet the guy with the whip has a keen eye for shading on stroke length (duration with blade submerged).
I've stroked an eight before. Even without being able to see anyone behind me, I had a pretty good idea who was pulling their weight and who had good form. At the elite level, I'm told everyone knows who pulled a good race.
In Primo Levi's books he talks about the hazards of being teamed up with the nearly goners: the ones who haven't got enough left to pull their share, and worse, the ones who no longer cared about life enough to slack for every extra second possible.
It would be a bit different sharing an oar than lugging railway ties in the snow with half a shirt.
Probably your best situation was to be paired up with the rookie who doesn't know his 4000 calorie work day is going to be rewarded with a 1500 calorie dinner. Until the third day when he faints and you get to pull both shares all by yourself.
http://en.wikipedia.org/wiki/Sawmill Prior to the invention of the sawmill, boards were rived and planed, or more often sawn by two men with a whipsaw, using saddleblocks to hold the log, and a pit for the pitman who worked below. Sawing was slow, and required strong and enduring men. The topsawer had to be the stronger of the two because the saw was pulled in turn by each man, and the lower had the advantage of gravity. The topsawyer also had to guide the saw so that the board was of even thickness. This was often done by following a chalkline. I was once told a story by a great ancestor that after a few weeks, the topsaw guy became so muscular he beat the crap out of the guy below, so the roles would often reverse, but that more often than not, the muscular guys took the easy jobs, and the small guys either ended up built like pit bulls, or were short for this world.
Anyways, if I'm reincarnated on a slave galley, I'd like to have that NYTimes reporter sitting beside me on the "desirable" side with the long lever arm, to discover the bio-mechanical joys of finishing your stroke at a 45 degree abdominal recline while I dent his head with my elbow every time he slacks off.
This has got to be the highest percentage of users with a UID less than mine to have posted in a single thread in a long time. I haven't counted, but over half of the posts as of the 60 post count mark were by users with a UID less than mine, which is WILD!
/. well enough too!
Yeah, I'm quite aware that this post was OT, I was just looking to get it pretty high up on the discussion. I know how to game
As far as the article, I'm surprised no-one has mentioned the Yonaguni civilization and what may have been lost from even back then!!?!?!! Well, of course, there is no guarantee that there actually was a civilization, but when it comes to how the ancients thought about machines, I'm more interested in the older civilizations and how they may have spread around the world into the civilizations that we all "know". Here's a clickie for those that don't know about Yonaguni (sorry for the paranoid site reference, but it's informative and has lots of viewables): http://www.morien-institute.org/yonaguni.html
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