[HN Gopher] Assyrian soldier diving with an inflatable goatskin ...
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Assyrian soldier diving with an inflatable goatskin bag (ca.
865-860 BC)
Author : type0
Score : 135 points
Date : 2021-09-18 22:08 UTC (2 days ago)
(HTM) web link (twitter.com)
(TXT) w3m dump (twitter.com)
| pbhjpbhj wrote:
| Fascinating, the second image attached to
| https://twitter.com/FedeItaliano76/status/143532682797161267...
| is good too -- I'm not settled in that confirming the second
| hypothesis (surface use), as the Twitter user says, it seems to
| me to also give stronger weight to the first (under water use).
|
| In this image the 'goatskin' users appear fully clothed in
| dresses (could they be scale armour or other weighted clothing),
| only one has a beard. A person without a goatskin appears "above"
| them (could be behind depending on perspective) and IMO appears
| to be getting shot with arrows. The "divers" aren't wearing
| onion-shaped helmets. The goatskins appear to be fixed to the
| belts on their waists.
|
| One could interpret this as showing underwater swimming to avoid
| archers.
|
| Perhaps it was an idea, rather than a practiced activity? Maybe
| the goatskin has rocks in it too, to balance buoyancy? Perhaps
| the carrying a rock bit was not shown for fear of letting enemies
| in on the idea!?!
|
| [But yes, more probably a floatation device; fun to speculate
| though. Would particularly be interested to look at perspective
| in Assyrian bas reliefs]
|
| Really interesting, would love to hear some Assyrian historians
| debate this.
| dakial1 wrote:
| I think it is settled among historians that this is a flotation
| device. There are multiple descriptions about it around: (http:
| //www.iro.umontreal.ca/~vaucher/History/Prehistoric_Cra...)
| spywaregorilla wrote:
| I wonder if the scene depicted is much of an action scene
| then, or if the archer is just there because they're
| soldiers. I'd imagine swimming with this goat bag is hardly
| tactically viable in almost any situation.
| woofie11 wrote:
| I would too. Unfortunately, the last Assyrian historians died
| nearly 3000 years ago.
| fsckboy wrote:
| There are still Assyrians today, they are a persecuted
| Christian minority in the lands currently disputed between
| Shia and Sunni factions.
|
| https://en.wikipedia.org/wiki/Assyrian_continuity
| woofie11 wrote:
| That was a fascinating article. Thank you!
| killjoywashere wrote:
| The work of submerging air at atmospheric pressure vastly
| exceeds the potential energy value extractable from the oxygen
| in terms of ATP. He's using it to float.
| seiferteric wrote:
| That's what diving weights are for.
| caymanjim wrote:
| I was thinking that as well; it's not going to get you more
| than a few breaths of air, and it's not going to be easy to
| submerge with one. Even bogged down with weapons and armor, I
| suspect it would be impossible to submerge while holding
| something that large filled with air.
| mod wrote:
| Even if you could submerge it, it would require ridiculous
| effort to hold it submerged. I doubt one could swim across
| a body of water with weapons, armor, and a submerged
| goatskin bag and expect to make it very often.
| trhway wrote:
| >The work of submerging air at atmospheric pressure vastly
| exceeds the potential energy value extractable from the
| oxygen in terms of ATP. He's using it to float.
|
| he is wearing some armor, definitely head helmet - that
| allows to balance the floatation, and would be beyond most
| human capabilities without the goatskin. So he achieves 2
| goals simultaneously - extra air for prolonged diving as well
| as diving while donning some armor. That goatskin is like
| 20-30 liters - good for several minutes of breathing and
| those 20-30kg of extra floatation allow for the typical
| armor/chainmail and weapons.
|
| There is no issues with holding it submerged like other
| commenters suggest as he keeps it under the body, so the main
| force of those 20-30kg pushes onto his body up, and if
| anything it is very easy to belt it to the body so it
| wouldn't need any hands involvement to be maintained under
| the body.
|
| There is also no issues with drawing breath as suggested by
| others as the goatskin is under the same water pressure as
| his lungs.
| freeflight wrote:
| _> One could interpret this as showing underwater swimming to
| avoid archers._
|
| Could also be the scene of a siege, the swimmers trying to
| traverse a river with heavy currents, indicated by the swirls
| in the water.
|
| In that scenario the archers would give them covering fire from
| the defending soldiers in the castle structure.
|
| This could also explain the archers wearing different helmets:
| They belong to different sides in the conflict.
| nradov wrote:
| He's swimming on the surface. That bag would be too buoyant for
| diving.
| keville wrote:
| What about needing to counter the weight of the sword depicted
| just ahead of the soldier?
| AndyMcConachie wrote:
| See the first reply.
|
| > Another possible explanation for the above scene is that the
| soldier is helping himself to float by blowing into the
| goatskin, which is therefore a sort of floating device.
| wavefunction wrote:
| Why have an inflatable goatskin that you're inhaling from for
| swimming on the surface? Considering the fish next to him it
| seems more likely the artist left out the boring aspects of
| holding rocks or whatever to reduce buoyancy.
| biot wrote:
| Did you also consider the horse depicted below the fish?
| wavefunction wrote:
| Horses and the sea have a long history.
| nradov wrote:
| Artists don't always use realistic perspectives, especially
| not that long ago. The swimmer isn't inhaling, he's blowing
| into the goatskin to keep it inflated. It's just like a
| modern inflatable life vest which has a manual inflation tube
| to use if the automatic inflator fails. There are no rocks
| (although ancient free divers sometimes did hold rocks to
| dive down faster).
| jccooper wrote:
| Who says he's breathing from it? More likely he's breathing
| into it (like bagpipes) to keep it inflated. It's not likely
| to be perfectly airtight.
| [deleted]
| sbacic wrote:
| Yep. One of the first issues you'll encounter when learning to
| dive is getting your body to sink (that's what all those lead
| weights are for). I also don't think an inflatable goatskin has
| enough air capacity to be relevant.
| pbhjpbhj wrote:
| Did you see the second image -- how about if it was deflated
| and used as a re-breather and was principally to stop exhaled
| bubbles from giving your position away to archers as you
| crossed a river/moat?
| caymanjim wrote:
| One cubic foot of air displaces one cubic foot of water
| (compression notwithstanding). A cubic foot of water weighs
| 62lbs. I think you're vastly underestimating the bouyancy of
| an inflated bag. Try to pull a standard birthday party
| balloon underwater. It's nearly impossible to do. You would
| need a tremendous amount of extra weight to submerge a
| goatskin full of air.
| sbacic wrote:
| I was referring to the bladder's capacity to store
| breathable air. I'm well aware how buoyant an inflated bag
| (or a wetsuit, for that matter) can be :)
| zeteo wrote:
| Agreed, also I think he's breathing into the bag not out of it.
| If you have a flotation device that's not fully sealed then you
| need to periodically re-inflate it a bit. It's the equivalent
| of keeping a leaky boat afloat by bailing water.
| LeifCarrotson wrote:
| Additionally, a bag of air of that volume would not give much
| time underwater - maybe an extra breath or two. The extra
| effort and drag of carrying the bag would make it less
| effective than just diving.
|
| A modern steel SCUBA tank is typically pressurized to 200 bar,
| or about 3000 psi, making it 200x more useful than a bag. An
| inflatable ball is only inflated to about 0.5 bar/8 psig, human
| lungs are only capable of about 0.1 bar/2 psi. This would be
| about as useless underwater as one of those little one-liter
| bottles with integrated mouthpiece that scams show being
| inflated with a bicycle pump...
|
| Still cool to see swimming like this depicted in 800BC! Puritan
| attitudes towards swimwear as well as imperial navies
| conscription of non-swimming sailors seem to have caused us to
| imagine swimming as a modern activity that we do better than
| anyone in history, but I expect that people throughout history
| did lots of swimming.
|
| I also find it interesting that he's depicted wearing a helmet,
| I wonder if that's to identify that "this guy's an Assyrian
| foot soldier" or if they actually swam in their helmets!
| MisterTea wrote:
| When I was a kid we had an above ground pool that was about 3
| feet/~1 m deep. One day in the shed I found a 6 foot/2m
| length of hose that looked to be about the same diameter as
| the tube on the my little snorkel. Ah ha! I can attach this
| to my snorkel, tie the other end to a pool float and breath
| under water like a diver!
|
| My idea did not work out as planned. At the surface I was
| able to breath through the hose but once I tried to "dive"
| down I found that drawing a breath was difficult. At the full
| depth I could not draw a breath. I told my father later on
| (who was an engineer) and he explained the physics of water
| pressure.
| robocat wrote:
| That was dangerous due to the risk of hypercapnia:
| "increased CO2 levels could lead to unconsciousness which,
| if happening while in the water, can result in drowning.".
| Note that our breathing is regulated by the amount of CO2
| in our bloodstream, not the amount of oxygen. There is a
| fantastic explanation of the danger here:
| https://blog.daneurope.org/en_US/blog/are-full-face-
| snorkeli... There are safety regulations to limit the
| volume of air inside a snorkel (the dead space).
|
| "Snorkels constitute respiratory dead space. When the user
| takes in a fresh breath, some of the previously exhaled air
| which remains in the snorkel is inhaled again, reducing the
| amount of fresh air in the inhaled volume, and increasing
| the risk of a buildup of carbon dioxide in the blood, which
| can result in hypercapnia. The greater the volume of the
| tube, or the smaller the tidal volume of breathing, the
| more this problem is exacerbated."
| --https://en.wikipedia.org/wiki/Snorkel_(swimming)
| cesis wrote:
| Strictly speaking every 10m under water increases pressure by
| one bar. So elastic bag 10m under water would take up 2x less
| space.
| clipradiowallet wrote:
| > This would be about as useless underwater as one of those
| little one-liter bottles with integrated mouthpiece that
| scams show being inflated with a bicycle pump...
|
| These irk me too! The pictures _never_ mention that the hand
| pump in them, isn 't a bike pump at all, it's a high-pressure
| pump that you will have to pump for nearly an hour. I see
| these constantly in the "suggested products" when shopping
| for any diving kit on amazon.
| Retric wrote:
| It's more complicated than that because the bag can be
| deflated unlike a scuba tank so you're benefiting from normal
| atmospheric pressure. Assuming the scuba tank was filled with
| normal atmosphere and this bag was about the size of
| someone's torso, it's probably much closer than 200x.
|
| First you don't normally do ultra slow deep breathing with
| scuba gear which can increase the amount of oxygen extracted.
| Next the volume of scuba tanks isn't that high normally and
| you lose reserve capacity. My guess is up to 5 minutes of air
| in a bag is probably possible which could be a quite a bit if
| their pearl diving or something.
|
| On the other hand it could simple be an inflatable bag useful
| as a flotation device.
| nradov wrote:
| None of that is even close to correct. Are you a scuba
| diver?
| Retric wrote:
| Not regularly and only very shallow so my recall of the
| details isn't great. But I do recall asking about even
| slower breathing and the response was it extracted more
| oxygen but wasn't recommended due to the risks of
| disorientation. I think the 2x was in relation to failing
| to do slow deep breathing though.
|
| As a sanity check 6l of air per minute x 5minutes is 30l
| which is about the size of your torso. Assuming that bag
| started that size and got completely emptied it's about
| right. The volume would decrease rapidly with depth but
| the available oxygen per breath would increase to
| compensate.
|
| Unless you have something specific to correct?
| jessaustin wrote:
| That's about the size of _my_ torso, but I 'm fat as
| hell. I suspect the average ancient swimming warrior was
| in better shape.
| Retric wrote:
| Unless your short your estimate seems odd. The torso is
| about 1/2 the volume of the average adult and people are
| close to the density of water of 1kg/l or 2.2lb/l. So 30l
| would be the expected torso volume of someone weighing
| ~60kg or ~130 lb.
|
| Edit: "47% trunk and neck" so 40% torso would be 75kg and
| 165lb seems reasonable as a smaller person would also
| need less air.
| jessaustin wrote:
| 30L is 8 gallons. The average torso is somewhat longer
| than a five gallon bucket, but of course it's much
| slimmer than a five gallon bucket. An eight gallon
| bucket, if it existed, would be larger yet. I would
| question both the assumption that a torso is half the
| volume of a human and the further assumption that the
| density of humans is uniform. Obviously the thorax, which
| contains the lungs, is less dense than the legs, which
| just have muscles and massive bones with a thin layer of
| fat.
|
| Sorry it took a while to respond; I got rate-limited this
| morning.
| Retric wrote:
| Ok in anatomy the torso is shoulders to anus. Various
| other places use shoulders to top of hip bones.
| https://en.wikipedia.org/wiki/Torso vs
| https://www.wikihow.com/Measure-Torso-Length
|
| I never realized it was ambiguous, but the image shows
| roughly chin to balls so whatever term you want for the
| longer one. https://twitter.com/FedeItaliano76/status/143
| 529525743702835...
| nradov wrote:
| You're just so far off that I don't even know where to
| begin. Either the person you asked was completely
| confused, or you didn't understand what they told you. As
| a starting point I would recommend reading the US Navy
| diving manual.
|
| https://www.navsea.navy.mil/Home/SUPSALV/00C3-Diving/Divi
| ng-...
| eric_h wrote:
| Can confirm - I went on a bunch of dives with a former
| Navy Seal and he used less than half the air on any given
| dive than the rest of us (who were all only regular or
| advanced certified) did. His explanation was that he'd
| just mastered the meditative mindset/breathing technique
| to use as little air and energy underwater as possible.
| nradov wrote:
| Mindset and breathing technique is certainly important in
| minimizing open circuit gas consumption, but it's not the
| only factor. Some people just have a naturally higher
| tolerance for CO2 loading (the instinct to breathe is
| driven more by increase in CO2 levels rather than lack of
| O2). Perfect buoyancy control helps a lot since you're
| not wasting energy on depth keeping. Equipment
| configuration should be streamlined to minimize drag. A
| high level of physical fitness also allows you to keep
| your breathing under control during periods of exertion,
| like finning against a current.
|
| But I've also seen former military divers who had
| relatively high gas consumption. Some units mainly use
| closed circuit rebreathers or surface-supplied gas where
| breathing rate doesn't matter.
| Retric wrote:
| That's true, but irrelevant in this case as in the short
| term people are O2 limited not CO2 limited which is why
| the world record for holding ones breath goes up by
| breathing pure oxygen.
|
| It's also one of the reasons I was asking for examples as
| I assumed you where making assumptions that didn't apply.
| aix1 wrote:
| > The volume would decrease rapidly with depth but the
| available oxygen per breath would increase to compensate.
|
| > Unless you have something specific to correct?
|
| Firstly, how would you bring the highly buoyant bubble of
| air underwater, in a controller manner?
|
| But let's say, for the sake of argument, that you could.
| Even though the volume of the bubble would indeed
| decrease with depth (e.g. it would halve at 10m), the
| volume of _each breath_ would remain roughly unaffected
| by depth. This is the reason scuba divers deplete their
| air supply faster the deeper they go.
|
| The amount of _available_ oxygen per breath is
| irrelevant. Even at sea level the exhaled air is about
| 16% oxygen (down from 21%). Giving the body access to
| more oxygen per breath won 't make the air supply last
| longer[*].
|
| [*] Interestingly, there's a point at which oxygen
| becomes toxic. The circumstances in which this happens is
| well outside the parameters of this discussion, however.
| https://en.wikipedia.org/wiki/Oxygen_toxicity#Underwater
| lb1lf wrote:
| > Even at sea level the exhaled air is about 16% oxygen
| (down from 21%). Giving the body access to more oxygen
| per breath won't make the air supply last longer[*].
|
| -Incidentally, in the survival suits we wear when
| helicommuting in the North Sea contain a rebreather
| device - which is simply a small bag in the suit's lining
| with a mouthpiece and a valve.
|
| The idea is that when getting underwater is imminent, you
| take a few deep breaths. When you exhale into the bag,
| you can then draw the spent air back in for another gulp
| or two of air.
|
| The idea being that in a couple of breaths you'll either
| be in the clear or dead - so a couple of extra breaths is
| all you realistically need. (Ever the cynic, I suspect
| part of the reasoning behind it is to keep you busy and
| un-panicked in your last few seconds alive, but
| anyway...)
| Retric wrote:
| I am not saying it's practical or their going to spend
| time at significant depth. The utility might have been a
| simple game of who could stay under water longer. That
| said, spending noticeably longer at 5-10m with an air
| filled bag weighted down by stones is a very long way
| from oxygen toxicity or the bends.
|
| As to available oxygen, removal of CO2 is major
| limitation in the long term and that's limited by partial
| pressures so having more available oxygen doesn't help in
| the long term. However, the world record for holding your
| breath is 22 minutes on pure oxygen so if we are talking
| a 7 minute vs 12 minute dive CO2 is going to be
| irrelevant.
| nradov wrote:
| Swimming was quite common in ancient Mediterranean area
| societies. They even did a lot of breath hold free diving,
| hunting for sponges and shellfish.
|
| Modern swimmers probably are better than anyone in history.
| An optimal front crawl stroke technique isn't intuitively
| obvious at all. There have been significant improvements just
| in the last few decades.
|
| https://en.wikipedia.org/wiki/Front_crawl#History?wprov=sfla.
| ..
| setr wrote:
| Don't know about "optimal", but apparently the front crawl
| itself isn't too novel.. from that wiki page:
|
| > The "front crawl" style has been in use since ancient
| times. There is an Egyptian bas relief piece dating to 2000
| BCE showing it in use.
| [deleted]
| optimalsolver wrote:
| Is Federico Italiano really the Twitter poster's real name? Coz
| that's about the most Italian name ever.
| stevespang wrote:
| Yep, unless he weighted himself down with bags of rocks which is
| possible (dive weights), the bag would be too buoyant and he
| would not be able to swim downward to depth. He would likely need
| ropes or straps to keep the bag to his body, instead of
| struggling to keep the bag from slipping away.
| abeppu wrote:
| I think it's interesting that he's shown swimming mostly nude but
| wearing a protruding hat which seems pretty impractical. Is the
| hat symbolic?
| ddalex wrote:
| In certain societies (Thracians, for example) the type of hat
| and decorations on it would indicate the social status of the
| wearer.
| abeppu wrote:
| Yeah, in general that wouldn't be surprising. The OP
| describes this guy as a "soldier", but I wonder if there's
| enough info to know whether he's just a soldier perhaps
| someone more important.
| tragomaskhalos wrote:
| A related oddity - according to "Navies of the Napoleonic Era",
| Turkish ships had higher decks than was normal for other navies
| allegedly to allow for elaborate headgear, even though this
| actually compromised the stability of the ships.
| handrous wrote:
| Is that a hold-over from Byzantium/Eastern-Roman-Empire, kept
| after the Turkish conquest? They were all about elaborate
| hierarchies of ranks and titles, often expressed through big
| hats or helmets.
| notorandit wrote:
| You cannot dive with an inflated goatskin, unless you carry extra
| weight, like stones.
| 3pt14159 wrote:
| Swords and armour are heavy.
| wil421 wrote:
| Then you would just become buoyant and not even sink. Try to
| bring a basket ball to the bottom of a pool. Grab some bricks
| and a basket ball then see what happens.
| simonh wrote:
| As soon as you breathed in the air from the skin, you would
| lose the buoyancy form it and sink to the bottom.
| djrogers wrote:
| Umm, what do you think happens to the air in that skin when
| you breathe it? It goes into your body, and continues to
| provide buoyancy.
| simonh wrote:
| So the person doesn't inhale deeply and hold their breath
| beforehand, and submerges with empty lungs? That seems,
| well, not ideal.
| treis wrote:
| People exhale too.
| djrogers wrote:
| Not that heavy. Air displaces about 62 lbs of water per cubic
| foot, so a goatskin the size of your torso would require more
| weight than a soldier could carry to offset it.
| tomtomistaken wrote:
| I think you are right and the depicted soldiers are not diving
| but floating. Maybe they carried their weapon in the bag, they
| all seem unarmed. Also I was wondering why they would
| continuously have to blow air in the sack. Probably they
| weren't airtight.
| dr_dshiv wrote:
| The Batavians used amphibious warfare, which was used by the
| Roman Empire to wage surprise attacks in Britain.
|
| https://en.m.wikipedia.org/wiki/Batavi_(Germanic_tribe)
| strangattractor wrote:
| I think he is drinking wine from a calfskin.
| codezero wrote:
| I mean, that's one thing to do when stuck in a river trying to
| flee angry archers.
| _bax wrote:
| And with the bathing cap...
| aaron695 wrote:
| Floating on sheepskin
|
| https://www.chinadaily.com.cn/travel/2012-11/15/content_1593...
|
| "Sheepskin rafts can be traced back to the Han Dynasty (206 BC-AD
| 220), when soldiers used them to ferry men and goods during wars.
| Local residents in Lanzhou used them to shuttle passengers, fresh
| fruits and vegetables across the river."
|
| Sheepskin raft becomes popular for tourists to sightsee along
| Yellow River in Gansu
|
| http://www.xinhuanet.com/english/2019-05/31/c_138105617_9.ht...
| Igelau wrote:
| Poor guy must be freezing.
| Borrible wrote:
| Using inflated animal skins as floating devices is rather old and
| widespread tech.
|
| Floats: A Study in Primitive Water-Transport:
| https://www.jstor.org/stable/2844455
|
| Animal Skin Floats :
| https://www.iro.umontreal.ca/~vaucher/History/Prehistoric_Cr...
|
| Roman military pontoons made from inflated animal skins:
| https://www.researchgate.net/publication/291033772_Roman_mil...
|
| Sheepskin rafts are known in China since the Han Dynasty (206
| B.C.-220 A.D.)
|
| The Assyrians did use inflated animal skin for their rafts.
| https://www.researchgate.net/publication/323672056_The_Refle...
|
| By the way, the tech may save your life:
| https://www.artofmanliness.com/articles/how-to-turn-your-pan...
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