Transcript

The Bow Invention Out of Necessity | Stephen Selby | TEDxHongKong

[Music] Well, this is all very difficult because you're all so young. Uh I don't know whether I'm the oldest person in the room and I've already been outshawn by somebody aged 13. Uh so this is a real challenge for me. But uh maybe uh given the white hair and the age uh and the fact that I look like the man who sells Kentucky Fried Chicken, uh it's it's it's nice that I'm here to talk uh to you about archaeology. It's true. I'm going to talk about archaeology, innovation and archaeology. Innovation and invention arising out of necessity 25,500 years before our time. So, um, forget the PowerPoint. I've got something to say. Uh, the best audiovisisual aid first, your your imagination. Okay. Um, this this stick. Okay, you can all see it, right? Anybody not able to see this stick? The power of peer pressure. This stick. All right. It's It's 5t long. All right. 1 m 50. I I lived in Mexico. All right. 2 in wide, 3/4 of an inch thick. All right. Now, I've got it here, and I want to bend it. I'm really strong. Under this fat is a six-pack abs. Bang. Did that wake you up? It broke. It broke. The stick broke. What was the problem? If I can work this, we might find out. Whoa. Look at these rainbows. Okay. Look at the right hand rainbow. This is the cross-section through the stick. When I bent it, it was bending over. And on the inside of that rainbow greenish color is a part of the wood that was subject to compression. It was being squeezed together. On the outside was a part of the wood that was being extended, pulled apart. And in the middle was a part that was being forced between those two types of tension. And this is the problem of designing a bow for shooting with. And a lot of my study has been in the archaeology of bows. And I'm going to speak to you for a few minutes about how this problem has been resolved thousands of years ago. The problem of dealing with the contradiction between compression extension and the forces of shearing that occur in between in material when you want to bend a piece of wood and make a good bow. My word breaks. I'm frustrated. Frustration is the mother of invention. What you can see on the right hand rainbow is what people came up with to deal with the problem. We wanted a material that could be compressed. We wanted a material that could resist being pulled apart. And we wanted a material that could deal with the forces that occur in between. And not surprisingly, people found that one piece of wood was never going to do the job. You can just about get away with it if you use a very long piece of wood. But if you want a small thing that you can carry around that's light that you can carry up on a horse then you have a different problem. The way to solve it three different materials one for the extension one for the shearing and one for the compression. Um, another problem just introducing the technology of bows is imagine the straight piece of wood and I'm pulling it. At first it bends and the force that my string is putting on the bow is going to pull the ends towards the middle. But very soon it's going to stop doing that. It's going to try stretching the wood. Well, that's a pretty silly thing to do. Have you ever tried stretching a piece of wood? Yeah, it doesn't work. So, another problem that people had was how do we stop the force changing from pressing the sides in? We'd want to stop the force from pulling the wood back. And the way they did that was to add levers. Asian bows have hard, stiff wooden ends which act as levers and help compress the material in between. And the result is that when you pull the bow back, instead of becoming more and more difficult to pull, actually it feels pretty well much the same all the way you're pulling, which is a very nice quality when you're trying to design a bow. So these are two design elements. Getting over the contradicting forces, that's one problem you want to solve. And then getting over this problem of the bow getting heavier and heavy as you pull it. A third technical issue with bows is the bow is supposed to push the arrow. It's not supposed to push itself. If you have the potential energy stored in the bow, but the bow is very heavy, the materials are very heavy, then all the potential energy of the bow is going to be used to move the material of the bow and it's not going to be used to move the arrow. So this is another problem we want to solve technically. How can we make the material of the bow as light as possible so that the maximum amount of potential energy is actually pushing the arrow out? the the way that in China and the uh various national agencies around China uh solved this in historical times was to use different types of material. Particularly look at the top right. This great big water buffalo here has wonderful long horns. And if you cut a strip out of the horn, that horn is just wonderful for accepting compression. Bamboo on the left is very good at accepting a shearing force. It's just a wonderful material to put in the middle. And we go back to our water buffalo again because he has another useful product. The useful product is the senue along his backbone. If you take that senue out, I suggest you kill the buffalo first. Take the senue out and dry it. Remove all the fat. And you use a hammer to break it up. You come up with threads like hair, nice white hair like this. Threads of hair which are very, very good at resisting extension. Carbon fiber. BMW, eat your hearts out. 3,000 years ago, we had carbon fiber. You mix that with glue, attach it to the bamboo, put the horn on the inside, and you have three lightweight components, ideally suited to resisting extension, dealing with compression, and accepting sharing. And that is the basic technology of an Asian composite bow. Uh here's an old bow that I've cut up. If you look, you can see the sections. And I'm sorry that it'll be pretty small for some of you, but in those sections along the bottom, you can see a black bit at the bottom, which is the horn, a piece in the middle, which is the bamboo, and a grayish bit at the top, which is the layer of senue. And you can see how it's distributed along the body of the bow. And at the very end, and you can see it very clearly in the top two illustrations, those long levers which make sure that as we pull back on the string, instead of stretching the wood, we're actually compressing the middle part. Now, I'm going to go back to archaeology. So we find that in these items uh like this bow that we uh excavated in Sinjang along with the Sinjang famous the the mummies of Shinjang. Each male was uh buried together with a bow and arrows and those just like the mummies have been excellently preserved and we can see the structure. We can uh these are some of the drawings that I started working on. um very very complex. Uh we were absolutely amazed at how complex the uh distribution of senue and bow and wood was. The reason they were so complicated was necessity. Their access to materials was very limited. They had the uh horns of goats. They had the tamarisk bush. No long bamboo and no water buffalo horns. They had to make do with what they could get and they ended up with a very very complex con construction. This is a uh my drawing through one section which shows the complexity of how little bits were joined together. These people had time in the winter uh from about October to March. It was desperately cold. Moving about with their animals or planting their crops was impossible. They would be in their tents or in their houses. And they would have plenty of time to put these tools together, the bow and the arrow that they would use in protecting their families or in hunting for food. Um, and interestingly, uh, we did a lot of research on how to actually construct this bow. And there's a wonderful golden vase that's now in the Hermitage Museum in Lenningrad, which actually shows a man bending his bow, exactly the same sort of bow that we have excavated uh, in Yanghai Cemetery in Shinjang. And most exciting of all, and this is one of the projects that I'm very keen on promoting, we made one. A Canadian uh Adam Karpovich in Canada took the technical drawings. The top is the original item which we excavated and at the bottom Adam created the bow using absolutely the same techniques and technology. He said it drove him mad. It was so complex. Those people had time and probably six or seven people were working in the family doing parts of it. For one person to do it, it was terribly complex. But he achieved it. We ended up with a working model of a bow that had been used 2500 years ago. Um the the Sunungnu were a tribe uh who were very active in China's Hand Dynasty. So about 200 uh BC uh up to about 200 AD. And we excavated tombs. The Sumna had very interesting way of of of burying people. Um, they would bury a man in a grave with his bow and leave him for two years and then dig it all up again, smash the skeleton, break the bow, set fire to it, dump a dead horse on top, and cover it with earth. Go figure. Anyway, what it means is that anytime we excavate one of these bows, we get one half. So, we got I got one half. We looked at it. We x-rayed it. And you could see that there are all sorts of small bone reinforcements that sharpen the x-ray that we wouldn't have been able to see just looking at it with the uh uh naked eye and Photoshop. Using Photoshop, we recreate the whole bow. So now we have a reasonable recreation of that bow as it was before you put the string on. Uh remember you don't just stick the string along the the the gap at the top. That whole bow had to come all the way back over. And so again we found a very talented bow maker uh Chabaga in Hungary. And the uh on the right you can see his reconstruction of the bow. Here is another very complicated technology. Here the the Sununglu have made their limbs of their bow the moving part very wide. And there you can see what it's like being pulled. And there's a an ancient picture of someone a bit later than the Sunundu using the bow on horseback. I also shoot on horseback. It's not quite as difficult as uh wearing skates and hitting a piece of cow but it's it's pretty difficult. And um they work fine. They are very very fast and they're very very stable. I just want to finish quickly with these inventions. These are Chinese inventions to do with archery. The Chinese invented 3,000 years ago a crossbow that could shootum dum dum dum just by pulling a lever over and over again. They invented the gun sight. They invented the bronze crossbow mechanism. And by the way, and I haven't mentioned it there, they invented the safety catch to stop a crossbow being fired accidentally. and they invented on the top right a bow that you could just fold down the middle with a hinge. Uh so necessity thousands of years ago has given rise to innovation and now our innovation is to take these ancient inventions and recreate them, build them again, make them work so that archaeologists are not just looking at dead material, but they have a chance to actually lift these items up in their hands, pull the string, get a feel for how it works. So that these dead things are now talking to us once again. Thank you very much.