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."

Library of Alexandria

[Bananatree3]

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.

The History channel has a program on some of these amazingly complex ancient machines [history.com]

Re:Oh, the irony!

[techno-vampire]

This, of course, ignores the fact that in Greek times the oarsmen of a ship were paid professionals, not slaves. I doubt that there were any galley slaves in the Greek ships that won the battle of Salamis. Not sure about the Persians, though.

Re:Galley slaves had other worries...

[Mordok-DestroyerOfWo]

To be completely fair ramming of ships wasn't a common practice until well after the Bronze Age. Galleys and other warships were built extremely solid and ramming was used more as a way of getting your fighters over to the other ship than to actually debilitate it. Now if you want to talk about wooden shrapnel from oars being destroyed the hypothetical slave would be equally at risk wherever they were on the ship. In addition even if the slaves nearer the ship had to move their arms a lesser distance, they still had to use their legs to force the oar through the water. The fact that distance between rowing stations on early medieval Ottoman galleys is roughly equal throughout the length of the ship says that the distance covered by the oar would be equal throughout as well.

Re:Galley slave would want to be toward the hull

[icegreentea]

Completely true. A galley slave really wouldn't care. Which is why the Greek States by and large didn't use slaves. Almost all oarsmen were freemen, and they had to be somewhat professional. Athens (for example) built its wealth and its 'empire' on its navy, and thus there was a sense of pride in serving the navy. Not to mention, when you have 170 oarsmen, they have to work as a coherent team. Getting 170 slaves who really don't want to be there to work properly would be detrimental. In cases where slaves were pressed into service (in emergencies or what not) they were sometimes rewarded with freedom after serving.

Re:Oh, the irony!

[Petrushka]

You're thinking of Athens, not of Greece generally, and even Athens used slaves in its navy. Hence the social importance of the battle of Arginousai: after the battle the assembly voted to give freedom to slaves who fought in the battle.

Re:Other great knowlege repositories

[TapeCutter]

"they never even invented the wheel"

So how do you explain wheels on Mayan toys?

Re:Other great knowlege repositories

[Anonymous Coward]

Arabic numerals reached what is now Spain in the 900s, when it was ruled by the Berbers.

So, no: the Spanish did not have anything to learn from the Mayans regarding number systems in the 1500s. They had already known it for 600 years! It was no longer an exciting new technology.

(By comparison, calculus was found by Newton only 320 years ago.)

Not slaves.

[Anonymous Coward]

OK - I know a LOT about Greek warships and nearly every aspect of this article that talks about Greek ships is utterly bogus.

Firstly: Greek oarsmen were not slaves - they were free men...and quite well paid too. In times of war, each town or village would put forward their own team of oarsmen to man a ship - and competition between villages to produce the finest and fastest oarsmen was intense. It wasn't until much later when the Romans started using oared warships that slaves would have rowed them. The Greek galleys were like the sportscars of the era - fast, sleek - efficient. The guys who rowed them were highly trained athletes. In any case, you couldn't possibly use slaves in a Greek ship because there were about 150 oarsmen and only about a dozen other people on board. In the face of a battle - there is no way that 12 overseers could possibly prevent 150 slaves from simply rowing off in the direction of home never to be seen again! The Roman ships were slow, lumbering and largely ineffective - basically just platforms on which the Romans could pretend they were fighting a land battle. They had far more soldiers on board than the Greeks did (another reason they were slow) - plenty enough to stop the slaves from revolting.

Secondly: The total amount of work you have to do doesn't depend at all on where you sit in the ship. If you are further from the fulcrum, you don't have to pull with so much force on the oar - but you have to pull it faster in order to keep up with the other oarsmen. Since work done equals force times distance - you have to do exactly the same amount of work per oar-stroke no matter where you sit...and in order to keep that forest of oars from getting all tangled up - everyone has to do the same number of strokes per second. Hence the total energy per hour of rowing doesn't depend on where you sit.

Thirdly: The REAL reason oarsmen preferred the middle rank is because they didn't get the direct heat of the sun bearing down on them like the top rank of rowers did. Furthermore, (and this was a running joke in the literature of the time) the guys in the bottom rank of oars sat in a position where the butt of the middle rank guys were pretty much right in their faces - and they'd get farted at ALL THE TIME! So the sweet spot was the middle rank - and that had nothing whatever to do with fulcrums and levers and such.