WEBVTT - TechStuff is Under Siege 0:00:04.160 --> 0:00:07.160 Get in touch with technology with tech stuff from how 0:00:07.240 --> 0:00:13.320 stuff Works dot com, Hale and well met. This is 0:00:13.400 --> 0:00:16.840 tech stuff and I am your host, Jonathan Strickland, senior 0:00:16.880 --> 0:00:19.720 writer for how Stuff Works dot com. And many of 0:00:19.760 --> 0:00:23.120 you know that in my life outside of the office, 0:00:23.880 --> 0:00:27.880 I'm also the occasional Renaissance Festival performer. If you did 0:00:27.920 --> 0:00:31.120 not know that, you know it now. I'm not ashamed 0:00:31.120 --> 0:00:35.440 of this totally. I've actually even appeared as my Renaissance 0:00:35.440 --> 0:00:37.920 Festival character on an episode of Stuff You Missed in 0:00:38.000 --> 0:00:40.600 History Class. I'm not going to tell you the episode 0:00:40.600 --> 0:00:42.360 title because I don't remember it off the top of 0:00:42.400 --> 0:00:45.000 my head, but I do appear in it, so it's 0:00:45.000 --> 0:00:48.720 a classic episode. I think might have been Sarah and 0:00:48.800 --> 0:00:52.720 Dablina as the hosts back in those days. Anyway, I'm 0:00:52.760 --> 0:00:58.160 performing at the Georgia Renaissance Festival this year season, and 0:00:58.640 --> 0:01:02.160 the opening day for the Renaissance Festival is the day 0:01:02.200 --> 0:01:06.920 after this podcast airs, so I thought, why not do 0:01:07.200 --> 0:01:11.160 an episode inspired by ye olden times? And yes, I 0:01:11.200 --> 0:01:14.479 know he is actually the We're going to go back 0:01:14.680 --> 0:01:17.600 quite a bit before the Renaissance because today I'm going 0:01:17.640 --> 0:01:21.560 to talk about siege engines. I thought it'd be kind 0:01:21.600 --> 0:01:24.720 of fun and sort of in the theme of looking 0:01:24.760 --> 0:01:28.000 back on history as I prepare to don my tights 0:01:28.000 --> 0:01:33.160 and doublet I'm sorry for that mental image anyway. What 0:01:33.319 --> 0:01:35.560 is a siege engine? While it's a device meant to 0:01:35.600 --> 0:01:39.920 allow an attacking army to gain entry to a fortified space, 0:01:40.760 --> 0:01:44.279 typically a fortified city or a castle, something along those lines, 0:01:44.319 --> 0:01:48.720 they're they're used to penetrate or destroy fortress walls or gates, 0:01:48.800 --> 0:01:52.400 and they tend to be enormous and they exert tremendous 0:01:52.560 --> 0:01:56.760 force in their operation. I'm going to focus on siege 0:01:56.840 --> 0:01:59.840 engines from ancient times to medieval history, but you should 0:02:00.040 --> 0:02:04.520 know that siege engines continued to evolve even after medieval era, 0:02:05.560 --> 0:02:09.720 even after the the invention of gunpowder and the distribution 0:02:09.760 --> 0:02:12.800 of gunpowder. To be fair, gunpowder had been invented for 0:02:12.919 --> 0:02:16.519 a very long time before anyone over in medieval Europe 0:02:16.520 --> 0:02:20.320 figured out how to use it as a means for weaponry. 0:02:20.639 --> 0:02:24.280 And uh also, gunpowder ended up making a lot of 0:02:24.320 --> 0:02:27.440 the traditional city defenses ineffective. I'll talk about that more 0:02:27.600 --> 0:02:31.480 later on in this episode, but siege engines were used 0:02:31.480 --> 0:02:35.160 in both world wars. Actually, but I'm gonna save that 0:02:35.240 --> 0:02:37.120 for a different episode. We're going to talk about the 0:02:37.200 --> 0:02:39.480 old stuff, this kind of stuff you might see in 0:02:39.480 --> 0:02:42.959 a movie about nights and royalty and stuff like that. 0:02:43.919 --> 0:02:48.880 So siege weapons were necessary to penetrate a fortified position, typically, 0:02:48.919 --> 0:02:51.000 like I said, a city or a castle. So why 0:02:51.000 --> 0:02:54.600 would you lay siege to such a place at all. Essentially, 0:02:55.160 --> 0:02:57.640 it's an effort to make the people inside surrender to 0:02:57.680 --> 0:03:00.800 the people outside. It seems pretty simple. Usually the people 0:03:00.840 --> 0:03:04.160 inside would include someone of importance who kind of had 0:03:04.160 --> 0:03:08.160 the authority to hand over the rule of law for 0:03:08.240 --> 0:03:12.160 that region to somebody else. And the word siege comes 0:03:12.200 --> 0:03:16.080 from a Latin word sederre, which means to sit, And 0:03:16.120 --> 0:03:19.320 that's pretty much what a sieging force does. It sits 0:03:19.360 --> 0:03:23.200 outside a fortified area and it waits. It also usually 0:03:23.240 --> 0:03:25.720 attempts to cut off supplies that are heading into the 0:03:25.760 --> 0:03:28.959 fortified location, both food and water and other things, to 0:03:29.040 --> 0:03:32.120 push the people inside to the point of desperation so 0:03:32.160 --> 0:03:36.560 that they surrender. But sometimes a long wait just isn't convenient. 0:03:37.040 --> 0:03:40.200 You've got places to go, people to meet, lands to conquer, 0:03:40.840 --> 0:03:43.760 so you can't really wait around for people to eat 0:03:43.800 --> 0:03:48.200 that last apple or to draw the last water from 0:03:48.240 --> 0:03:50.600 the well. You've got to find a way to speed 0:03:50.640 --> 0:03:52.560 things up a little bit. You've got to convince them 0:03:52.640 --> 0:03:56.960 that they need to give up, and maybe force them 0:03:57.160 --> 0:03:59.880 to give up, and that requires getting access to the 0:04:00.080 --> 0:04:06.840 place that's fortified. Thus siege engines. Now, archaeologists have uncovered 0:04:06.880 --> 0:04:11.520 evidence of fortified city walls from ancient cities all around 0:04:11.520 --> 0:04:13.240 the world, and in a way, you could say that 0:04:13.320 --> 0:04:17.000 human history is marked by innovations in ways to keep 0:04:17.040 --> 0:04:21.440 a people safe and other innovations designed to overcome those protections. 0:04:22.520 --> 0:04:24.919 It gets a pretty grim when you start thinking about 0:04:24.960 --> 0:04:28.200 specifics and you get down to brass tacks, as it were. 0:04:28.240 --> 0:04:32.200 But if ancient people had fortified walls, what did the 0:04:32.400 --> 0:04:37.919 ancient attackers use to breach those walls. Well, there are 0:04:37.920 --> 0:04:40.440 a couple of different tactics that don't involve siege engines 0:04:40.440 --> 0:04:42.719 at all. For example, you might try and use fire 0:04:42.800 --> 0:04:47.080 to weaken walls. You might tunnel under walls, either to 0:04:47.200 --> 0:04:51.039 collapse the wall so that they just fall down, or 0:04:51.240 --> 0:04:54.479 you end up just bypassing the wall entirely in tunnel 0:04:54.560 --> 0:04:56.479 into the place that you're trying to get access to. 0:04:57.560 --> 0:04:59.880 Or you might just use ladders to try and act 0:05:00.040 --> 0:05:02.680 us the top of the wall and scale it. Obviously, 0:05:02.760 --> 0:05:04.840 that could be dangerous if there are soldiers up at 0:05:04.839 --> 0:05:06.760 the top of the wall to push the ladders down. 0:05:06.880 --> 0:05:10.000 So you've got to hope that you can zerg rush 0:05:10.040 --> 0:05:12.960 it use a whole bunch of people all at once. 0:05:13.680 --> 0:05:15.240 If you don't know what a zer rushes, you need 0:05:15.279 --> 0:05:17.400 to go listen to the tech Memes episode that published 0:05:17.400 --> 0:05:22.080 not too long ago. So the ancients would start to 0:05:22.080 --> 0:05:25.159 construct massive tools to break through barriers. These are the 0:05:25.200 --> 0:05:29.719 siege engines. They're bigger than things like just a tunnel 0:05:29.920 --> 0:05:34.840 or a ladder, and arguably the oldest version of the 0:05:34.880 --> 0:05:38.840 siege engine is the battering ram. So I'm sure you're 0:05:38.880 --> 0:05:42.320 all familiar with the concept, but just in case. A 0:05:42.320 --> 0:05:46.120 battering ram is a large mass that can be swung 0:05:46.279 --> 0:05:49.800 so that it has its impact against a surface and 0:05:49.880 --> 0:05:54.239 that causes that surface to become damaged. In other words, 0:05:54.240 --> 0:05:57.680 it's like an enormous hammer breaking through a wall or 0:05:57.720 --> 0:06:01.440 a door, and an example could be just an enormous log. 0:06:02.440 --> 0:06:05.960 And the earliest battering rams were held by people, but 0:06:06.040 --> 0:06:09.880 that was problematic. People can only hold weight up to 0:06:09.920 --> 0:06:12.120 a certain limit, and then it's just too heavy to move, 0:06:12.839 --> 0:06:16.280 it slows them down and they remain unprotected and can 0:06:16.320 --> 0:06:19.279 be picked off by archers or people with slings or 0:06:19.320 --> 0:06:24.560 other projectiles. So you want to improve upon this idea. 0:06:24.760 --> 0:06:27.440 So another example would be a log that is hung 0:06:27.600 --> 0:06:31.560 from a wooden frame by various ropes, and the ropes 0:06:31.600 --> 0:06:34.360 allow the log to swing horizontally so that the end 0:06:34.560 --> 0:06:37.400 can crash into that vertical surface like a wall or 0:06:37.440 --> 0:06:40.800 a gate. Uh. This would allow you to have a 0:06:40.880 --> 0:06:43.560 much heavier battering ram than something you would have to 0:06:43.600 --> 0:06:46.000 carry by hand, because you could put it on this 0:06:46.360 --> 0:06:49.560 rope system and just swing it and as opposed to 0:06:49.600 --> 0:06:54.640 having to lift it. According to ancient historians, the earliest 0:06:54.640 --> 0:06:58.279 example of this technology was the brainchild of a certain 0:06:59.200 --> 0:07:04.080 pe frasm No of Tire, and I apologize for absolutely 0:07:04.279 --> 0:07:07.520 butchering the pronunciation of that name, because I'm certain I 0:07:07.560 --> 0:07:11.600 did anyway. This particular engineer would have lived sometime between 0:07:11.680 --> 0:07:15.520 five hundred and three fifty b C. And his His 0:07:15.840 --> 0:07:19.480 main invention was suspending a cross beam from a transverse 0:07:19.520 --> 0:07:22.120 beam for the purposes of swinging it as a battering ram. 0:07:22.160 --> 0:07:24.960 In other words, that design I was talking about hanging 0:07:25.160 --> 0:07:29.640 a wooden beam in a frame so that you can 0:07:29.880 --> 0:07:34.040 bash down a wall or a door. Now, typically you 0:07:34.080 --> 0:07:37.760 would also find that the frames holding these battering rams 0:07:37.760 --> 0:07:41.520 would be shielded by a roof, and often that roof 0:07:41.560 --> 0:07:46.280 would be covered with dampened animal skins. That would help 0:07:46.320 --> 0:07:50.240 cut down on the potential for fire. If you're defending 0:07:50.280 --> 0:07:54.120 city was using flaming arrows or burning oil or something 0:07:54.160 --> 0:07:57.680 on those lines, it would it would reduce the possibility 0:07:57.760 --> 0:08:00.840 that your brand new, shiny battering ram would just become 0:08:00.960 --> 0:08:06.520 kindling and uh. You would also protect yourself from other 0:08:06.600 --> 0:08:09.880 just basic projectiles and allow the operators of the battering 0:08:09.920 --> 0:08:16.600 battering ram to continue hammering against the wall or the door. Obviously, 0:08:17.240 --> 0:08:19.880 this was risky. You had to get access to the 0:08:19.920 --> 0:08:24.880 actual wall and according to Vitruvius, who was an author 0:08:24.960 --> 0:08:28.560 and engineer during the first century, the first person to 0:08:28.600 --> 0:08:34.760 create a fireproofed roofed battering ram was Kros the Carthaginian 0:08:35.840 --> 0:08:40.439 sometimes called Garross with a G the Carthaginian. Modern historians 0:08:40.480 --> 0:08:43.800 believe this person was alive sometime around the fifth century 0:08:43.880 --> 0:08:48.160 b C. And this was after the Iron Age that 0:08:48.240 --> 0:08:53.680 had happened several hundred years earlier, so it was very 0:08:53.720 --> 0:08:59.000 common for the attacking party to cap a battering ram 0:08:59.040 --> 0:09:04.559 with a large iron or otherwise metal cap, often shaped 0:09:04.640 --> 0:09:09.240 in the form of a battering ram like a literal ram, 0:09:09.800 --> 0:09:14.000 like a goat's head with horns. Uh. The iron would 0:09:14.000 --> 0:09:17.320 give the battering ram even more weight and resilience, and 0:09:17.320 --> 0:09:21.200 it would make it more effective. The animals would and 0:09:21.280 --> 0:09:23.920 you know it forms made it look more interesting. But 0:09:23.960 --> 0:09:28.000 they also could help with bashing through the the material, 0:09:28.160 --> 0:09:32.680 depending upon the shapes you were using, and uh, yeah, 0:09:32.679 --> 0:09:36.400 it was a pretty effective means of knocking down your 0:09:36.440 --> 0:09:39.960 basic city walls. Uh. They You also would see other 0:09:40.000 --> 0:09:43.000 improvements like pulley systems that would allow the battering ram 0:09:43.040 --> 0:09:46.400 to remain horizontal as it swung instead of tilting upward. 0:09:46.840 --> 0:09:49.439 So imagine a swing set swing. You know, when you're 0:09:49.440 --> 0:09:51.920 swinging on a swing, your feet tilt up in the 0:09:51.920 --> 0:09:55.320 air instead of staying horizontal unless you're actively moving your 0:09:55.400 --> 0:09:59.600 legs down. And uh, the pulley system would counteract that 0:10:00.040 --> 0:10:04.440 dency so that way you wouldn't be hitting the wall 0:10:04.679 --> 0:10:08.199 or door on an upward swing. It would be translated 0:10:08.200 --> 0:10:11.880 into a horizontal motion so that that momentum that you're 0:10:11.880 --> 0:10:15.200 transferring would be in the proper direction. And that's what 0:10:15.240 --> 0:10:18.479 we're talking about. The working principle behind the battering ram 0:10:18.600 --> 0:10:24.240 is the transfer of momentum momentum quick recap for people 0:10:24.240 --> 0:10:27.679 who don't remember their physics. It's the quantity of motion 0:10:27.760 --> 0:10:30.800 and a moving body. And the way you arrive at 0:10:31.400 --> 0:10:36.120 the quantity of momentum is by multiplying the mass of 0:10:36.160 --> 0:10:41.040 a moving body by its velocity, So that means momentum 0:10:41.080 --> 0:10:44.160 of a small object that's moving very very very fast 0:10:44.559 --> 0:10:47.000 can be the same as a large object moving much 0:10:47.040 --> 0:10:50.640 more slowly if the numbers work out the right way. 0:10:50.679 --> 0:10:52.960 But if something is really big and really fast, it 0:10:53.000 --> 0:10:56.000 has a whole lot of momentum to it. And I've 0:10:56.000 --> 0:10:59.000 got some funny stories about momentum. I had to explain 0:10:59.080 --> 0:11:02.760 this to a friend of mine. Uh. At the Renaissance Festival, 0:11:03.320 --> 0:11:09.040 there was a moment in a dance dance in which 0:11:09.160 --> 0:11:13.520 it is possible to steal the partner of another person um, 0:11:13.559 --> 0:11:15.880 in which I was trying to steal the queen from 0:11:15.880 --> 0:11:18.920 the king. The king being played by a guy who 0:11:18.920 --> 0:11:22.680 looked an awful lot like Henry the Eighth, including Henry 0:11:22.720 --> 0:11:27.280 the Eighth impressive mass, and this fellow collided with me. 0:11:27.360 --> 0:11:29.520 He gave me a little hip check, and he wasn't 0:11:29.520 --> 0:11:33.240 moving fast, but he did outweigh me by a significant amount, 0:11:33.480 --> 0:11:36.800 and so I went flying, and thus the transfer of 0:11:36.880 --> 0:11:42.600 momentum was demonstrated in a very real and ultimately painful way. 0:11:43.240 --> 0:11:45.920 I have since forgiven him. It actually was pretty funny, 0:11:46.000 --> 0:11:48.240 but I did sprain both my wrists and my ankle 0:11:48.280 --> 0:11:52.560 in that incident. So with battering rams, your desired outcome 0:11:52.640 --> 0:11:55.160 is to have a very large mass, and you wanted 0:11:55.240 --> 0:11:58.000 to move really quickly so that you can result in 0:11:58.080 --> 0:12:01.520 this large amount of momentum that transfer to a stationary 0:12:01.520 --> 0:12:05.000 object like the wall or the gate, and thus caused 0:12:05.040 --> 0:12:08.760 damage to it. So once battering ram started getting better, 0:12:08.800 --> 0:12:13.240 obviously cities needed to respond, and they began to reinforce 0:12:13.320 --> 0:12:16.880 their walls, making them thicker at the base and trying 0:12:16.920 --> 0:12:21.560 to create new strategies to repel battering ram assaults. My 0:12:21.640 --> 0:12:25.840 favorite battering ram is actually a fictional one. I like 0:12:26.000 --> 0:12:30.440 grond Grand was the battering Ram and Lord of the Rings. 0:12:30.480 --> 0:12:33.240 It was from Suron's army. They used it in the 0:12:33.320 --> 0:12:37.400 siegeen mins Tira, and it was ont long and had 0:12:37.400 --> 0:12:40.280 a metal cap that was shaped like a wolf. And 0:12:40.280 --> 0:12:42.600 the most of the depictions I've seen the wolf is 0:12:42.640 --> 0:12:47.120 also got some sort of fire or lava coming out 0:12:47.120 --> 0:12:52.720 of its mouth, making it pretty intimidating. Awesome image. Really. 0:12:53.880 --> 0:12:56.959 Another ancient season gen similar to this in the sense 0:12:57.040 --> 0:12:59.840 that you had to get super close to your target 0:13:00.400 --> 0:13:04.200 was the siege tower. This is a pretty simple concept. 0:13:04.400 --> 0:13:08.680 It's usually it's like a tower that's on wheels, and 0:13:08.800 --> 0:13:12.160 you push this tower up against the city wall that 0:13:12.280 --> 0:13:16.200 you want to uh you want to get past, and 0:13:16.559 --> 0:13:19.120 you have a gang plank at the top of the 0:13:19.160 --> 0:13:22.760 tower that you lower so that it rests on the 0:13:22.800 --> 0:13:26.559 city wall, and then your your force just goes through 0:13:26.679 --> 0:13:31.120 the siege tower, across the gang plank and into the city. 0:13:31.320 --> 0:13:37.439 Then you bipass the wall. Entirely very basic idea. Uh. Obviously, 0:13:37.760 --> 0:13:40.280 things could go wrong. The tower if it were set 0:13:40.320 --> 0:13:43.240 on fire, could end up causing you to lose quite 0:13:43.240 --> 0:13:46.959 a few of your men. Uh. And also there are 0:13:47.280 --> 0:13:50.440 lots of different ways to create obstacles to make it 0:13:50.480 --> 0:13:53.520 more difficult to get the tower up against a city wall. 0:13:54.320 --> 0:13:58.800 One of those would be moats. So your basic moat 0:13:58.960 --> 0:14:03.080 around a castle was really a defense against siege engines 0:14:03.160 --> 0:14:05.840 like this. Uh. It meant that it was much harder 0:14:05.880 --> 0:14:09.080 to get something like a siege tower up against the 0:14:09.080 --> 0:14:11.800 castle walls, because he had to get across the moat first, 0:14:11.880 --> 0:14:14.320 and the moat might either be dry or it could 0:14:14.320 --> 0:14:17.960 be filled with water. Not all moats were water. In fact, 0:14:18.000 --> 0:14:19.920 most of them weren't. Most of them were essentially just 0:14:19.960 --> 0:14:25.280 a very big ditch around the fort fortified area, so 0:14:25.360 --> 0:14:26.840 you would have to find a way to bridge that 0:14:26.880 --> 0:14:29.520 gap if you were an attacker, to allow your siege 0:14:29.520 --> 0:14:31.840 engine to roll over the moats, you had to build 0:14:31.920 --> 0:14:35.560 like essentially a temporary bridge to allow the siege engine 0:14:35.600 --> 0:14:38.520 to roll over it and get access to the city wall. 0:14:38.840 --> 0:14:41.880 And another defense was to redesign city walls in the 0:14:41.920 --> 0:14:44.480 first place. Engineers began to make walls that were very 0:14:44.480 --> 0:14:47.280 thick at the base and would slope from the top 0:14:47.440 --> 0:14:50.800 down to the base, and that slope meant that the 0:14:50.880 --> 0:14:53.680 top of the wall would be further away from a 0:14:53.720 --> 0:14:56.720 tower than the base of the wall. You know, it's 0:14:56.800 --> 0:15:01.720 because it sloped away from the out side. So that 0:15:01.760 --> 0:15:04.120 meant that your gang plank had to be longer in 0:15:04.240 --> 0:15:07.400 order to reach from the siege tower to the top 0:15:07.440 --> 0:15:10.760 of the city wall. And gang planks were really the 0:15:10.800 --> 0:15:15.040 weak points of the siege towers. Assuming that you've major 0:15:15.080 --> 0:15:17.600 siege tower as fireproof as you can manage, which again 0:15:17.720 --> 0:15:21.640 mostly involved putting the hides of animals on the outside 0:15:21.640 --> 0:15:24.360 of the tower and wetting them down, you know, drenching 0:15:24.400 --> 0:15:28.240 them in water as as much as you possibly can. Then, 0:15:28.480 --> 0:15:30.760 once you set down the gang plank and you have 0:15:30.800 --> 0:15:34.520 attackers going across, their most vulnerable when they are on 0:15:34.680 --> 0:15:39.040 that gang plank there standing over the height of the wall. 0:15:39.440 --> 0:15:42.640 There's probably a moat below them. The gang planks probably 0:15:42.680 --> 0:15:48.440 not incredibly sturdy or or stable. So the further away 0:15:48.840 --> 0:15:51.160 the top of the siege tower is from the top 0:15:51.160 --> 0:15:54.000 of the wall, the harder it is for the attackers 0:15:54.000 --> 0:15:57.160 to get over. So that was just a basic defense mechanism, 0:15:57.240 --> 0:16:00.640 was to build these sloping walls for cities to help 0:16:00.800 --> 0:16:05.520 protect against siege engines. Now, both siege towers and battering 0:16:05.600 --> 0:16:09.160 rams were made obsolete by the invention of cannons later on. 0:16:09.240 --> 0:16:11.440 I'll talk about cannons towards the end of this episode. 0:16:11.600 --> 0:16:14.240 Cannon's actually made those high city walls obsolete. In the 0:16:14.280 --> 0:16:17.400 first place. Higher walls were more vulnerable to cannon fire, 0:16:17.640 --> 0:16:20.880 and so the design of city fortifications had to completely change. 0:16:21.040 --> 0:16:26.280 Once those became a major element in warfare. At that point, 0:16:26.320 --> 0:16:28.920 those siege engines began to fade into history. You didn't 0:16:28.960 --> 0:16:32.000 really see them anymore. But I'll get more into cannons 0:16:32.000 --> 0:16:34.440 a little bit later in the episode. And I'm sure 0:16:34.520 --> 0:16:38.080 you've already noted that the major disadvantage to both battering 0:16:38.200 --> 0:16:40.240 rams and siege towers is that you have to get 0:16:40.240 --> 0:16:42.440 close to your target for them to work. If the 0:16:42.480 --> 0:16:45.840 defending city has set up other defenses like those trenches 0:16:45.960 --> 0:16:49.160 or pits or spikes, and they have stuff like hot 0:16:49.200 --> 0:16:53.360 oil or flaming weapons, getting close isn't terribly attractive. You 0:16:53.360 --> 0:16:56.520 would much prefer to batter the city from a distance, 0:16:56.520 --> 0:17:00.240 and so attackers began to design new engines, things that 0:17:00.280 --> 0:17:03.200 could allow attacks from much further away. So next I'll 0:17:03.240 --> 0:17:06.639 talk about some of the massive projectile weapons that were used. 0:17:07.200 --> 0:17:11.080 Uh and they relied purely on mechanical physics to hurl 0:17:11.240 --> 0:17:14.320 objects at walls. They're pretty cool. Before I do that, 0:17:14.640 --> 0:17:25.560 let's take a quick break to thank our sponsor. So 0:17:25.600 --> 0:17:27.840 the first projectile siege engine I really want to talk 0:17:27.840 --> 0:17:31.040 about is the ballista. And if you were to take 0:17:31.040 --> 0:17:33.400 a casual glance at a ballista, you might think it's 0:17:33.440 --> 0:17:37.760 an enormous crossbow, and it does resemble a crossbow. But 0:17:37.840 --> 0:17:41.840 they crossbow and the ballista work on two different principles, 0:17:41.960 --> 0:17:46.040 two different two different types of tension. Uh, the operation 0:17:46.080 --> 0:17:49.840 of the ballista depends upon two torsion springs, whereas the 0:17:49.880 --> 0:17:55.359 crossbow depends upon the natural tension of the bow itself. 0:17:56.800 --> 0:18:00.800 So let's talk about torsion springs. Torsion springs work by twisting. 0:18:00.840 --> 0:18:05.159 They store mechanical energy when you twist the torsion spring, 0:18:05.600 --> 0:18:09.280 and when you release the spring, it unleashes that mechanical 0:18:09.359 --> 0:18:13.199 energy through untwisting, so it's winding and unwinding. When you 0:18:13.240 --> 0:18:15.920 wind it up, you've got the mechanical energy, and when 0:18:15.960 --> 0:18:19.159 you let it go, it unwinds itself and releases that 0:18:19.240 --> 0:18:22.840 mechanical energy. To make a ballista, you need a pair 0:18:23.240 --> 0:18:26.000 of torsion springs that you can twist tightly so that 0:18:26.040 --> 0:18:29.159 when you release them, they unleash that mechanical force in 0:18:29.200 --> 0:18:31.760 such a way as to throw a projectile, typically a 0:18:31.880 --> 0:18:35.720 large dart with an iron tip at a target. Now, 0:18:37.880 --> 0:18:41.480 in ancient times, a torsion spring might look like a 0:18:41.560 --> 0:18:45.959 loop of some stretchy elastic material. That material was often 0:18:46.800 --> 0:18:51.439 either hair from animals sometimes humans, all woven together to 0:18:51.480 --> 0:18:55.280 make really strong ropes, or sometimes it was ligaments and 0:18:55.600 --> 0:18:58.520 other tissue that was turned into this kind of elastic 0:18:58.600 --> 0:19:02.399 material and then looped around a frame like a skein 0:19:02.680 --> 0:19:05.880 that's inside a frame. So imagine a loop of material. 0:19:05.920 --> 0:19:09.439 In fact, just imagine a rubber band, and imagine that 0:19:09.520 --> 0:19:13.399 you've got two pegs that are a few inches apart 0:19:13.400 --> 0:19:16.560 from each other. They're further apart than the length of 0:19:16.640 --> 0:19:19.200 the rubber band, so you have to stretch the rubber 0:19:19.200 --> 0:19:23.280 band a little bit two loop either end over the 0:19:23.320 --> 0:19:26.600 two pegs. Then you put more rubber bands that are 0:19:26.640 --> 0:19:29.480 the same length over those two pegs, so you've got 0:19:29.640 --> 0:19:33.119 a few of them, maybe four or five. These rubber 0:19:33.160 --> 0:19:38.680 bands represent an unwound torsion spring. If you then inserted 0:19:39.320 --> 0:19:44.080 a throwing arm, what would be considered like the shaft 0:19:44.160 --> 0:19:48.680 of a throwing arm, into that gap the middle of 0:19:48.720 --> 0:19:53.320 all those rubber bands, and then use it to twist 0:19:53.440 --> 0:19:58.040 the rubber bands in a circle, either clockwise or counterclockwise. 0:19:58.600 --> 0:20:03.320 You would create the hortion. This this twisted tension. You 0:20:03.400 --> 0:20:05.520 look them over and over again. You can do this 0:20:05.560 --> 0:20:09.120 with a pencil. So again, just have a rubber band. 0:20:09.119 --> 0:20:11.520 You can even have maybe someone stand in front of 0:20:11.560 --> 0:20:14.040 you putting their two thumbs up, and you loop the 0:20:14.160 --> 0:20:16.920 rubber bands around their two thumbs so that they're stretching 0:20:16.960 --> 0:20:20.399 them together. You put a pencil in there. You twist 0:20:20.480 --> 0:20:23.080 the pencil around a few times so that it's it's 0:20:23.080 --> 0:20:26.760 twisting the rubber bands, and you'll start building up that tension. 0:20:27.040 --> 0:20:29.880 If you let go of the pencil, then it will 0:20:30.000 --> 0:20:32.720 unleash all that mechanical energy and it will make the 0:20:32.720 --> 0:20:35.800 pencil flip around like crazy. Make sure you use an 0:20:35.840 --> 0:20:39.000 unsharpened pencil and be very careful with this sort of 0:20:39.000 --> 0:20:40.600 stuff because it might fly up and hit you in 0:20:40.640 --> 0:20:45.480 the face. But this is the basic principle of the ballista. Now, 0:20:45.480 --> 0:20:49.080 with the ballista, you have two of these torsion springs, 0:20:49.720 --> 0:20:55.160 and that meant that they're actually vertically aligned, not horizontally aligned. 0:20:55.960 --> 0:20:58.440 In other words, you would have imagine you have one 0:20:58.520 --> 0:21:02.120 thumb higher the the other thumb directly in front of you, 0:21:02.359 --> 0:21:05.000 and you put the rubber bands on so that you 0:21:05.080 --> 0:21:07.600 were holding the loop that way. That's the way the 0:21:07.640 --> 0:21:11.760 ballista torsion springs are aligned. You have to have those 0:21:11.840 --> 0:21:15.760 that vertical alignment and they're parallel to each other, and 0:21:15.840 --> 0:21:19.920 between the two torsion springs you have your stock or channel. 0:21:20.240 --> 0:21:24.000 That's where the projectile moves through. So with a crossbow, 0:21:24.080 --> 0:21:27.920 this would be where the bolt would slide through as 0:21:27.960 --> 0:21:30.680 it's being launched from the crossbow. Same sort of thing 0:21:30.680 --> 0:21:33.439 with a ballista. It's got that stock with the channel 0:21:33.440 --> 0:21:36.399 in it. That's where the projectile moves through it, and 0:21:36.440 --> 0:21:40.640 it's between these two vertically aligned torsion springs. So you've 0:21:40.680 --> 0:21:45.480 got your enormous dart loaded into your ballista, and you've 0:21:45.520 --> 0:21:49.679 got your two vertically aligned torsion springs. In each torsion spring, 0:21:49.840 --> 0:21:54.880 you have a throwing arm. Now, the torsion spring on 0:21:54.920 --> 0:21:59.520 the left side is wound counter clockwise if you were 0:21:59.560 --> 0:22:02.639 looking at it from above. That means that when the 0:22:02.680 --> 0:22:05.840 tension releases, it's going to spend its throwing arm in 0:22:05.880 --> 0:22:10.680 a clockwise direction. The torsion spring on the right side 0:22:11.280 --> 0:22:14.199 is the opposite. It's wound clockwise, so that when you 0:22:14.240 --> 0:22:18.160 release the tension, it will spin the throwing arm counterclockwise. 0:22:18.920 --> 0:22:21.359 And on the opposite end of the throwing arm, you 0:22:21.480 --> 0:22:25.480 have a line attaching the two together, a rope if 0:22:25.480 --> 0:22:29.440 you will or string this rope is looped around the 0:22:29.600 --> 0:22:32.320 end of your projectile. This is the thing that's going 0:22:32.400 --> 0:22:36.040 to transfer the force to the projectile and make it 0:22:36.160 --> 0:22:40.480 fly at your target. So just imagine you've got this 0:22:40.520 --> 0:22:44.080 crossbow looking thing in front of you. The two arms 0:22:44.080 --> 0:22:47.280 of the ballista in its rest position you haven't wound 0:22:47.320 --> 0:22:52.040 it yet, are extended outward to the side. So the 0:22:52.200 --> 0:22:55.320 left one is is almost parallel with the front of 0:22:55.320 --> 0:22:57.080 the ballist, of the right one is almost parallel with 0:22:57.080 --> 0:23:00.240 the ballista, and you have a device called a wind us. 0:23:00.800 --> 0:23:03.680 The windlass is what allows you to crank back those arms. 0:23:03.720 --> 0:23:08.159 It's creating tension in those torsion springs, so it starts 0:23:08.160 --> 0:23:11.359 to twist the torsion springs and as a result, the 0:23:11.440 --> 0:23:16.200 two throwing arms start tilting back towards you. It's that 0:23:16.440 --> 0:23:20.639 they've bend backwards, although the torsion the throwing arms themselves 0:23:20.680 --> 0:23:23.240 are not bending. It's just the torsion springs are are 0:23:23.400 --> 0:23:27.600 rotating as you're twisting them. Uh, so they've been backward. 0:23:27.680 --> 0:23:29.920 Now that means that you start getting slack in that 0:23:30.040 --> 0:23:35.200 rope that's between the two ends of the throwing arms. 0:23:35.760 --> 0:23:38.320 You can use that slack to put it behind your projectile, 0:23:38.840 --> 0:23:42.360 and when you release the tension on those torsion springs, 0:23:43.080 --> 0:23:47.680 they untwist that pulls the throwing arms forward, and that 0:23:47.920 --> 0:23:52.800 pulls that that rope forward as well, transferring the energy 0:23:52.840 --> 0:23:57.040 to your projectile and shooting it at your target. It's 0:23:57.080 --> 0:23:59.960 a pretty cool to see this, I mean, it's interesting 0:24:00.000 --> 0:24:03.199 to see this as two torsion springs as opposed to 0:24:03.240 --> 0:24:07.439 a crossbow, which would just use the tension of the 0:24:07.480 --> 0:24:10.520 material itself, the wood, if you will, of the bow. 0:24:11.400 --> 0:24:13.560 It's all due to mechanical physics. You don't need any 0:24:13.640 --> 0:24:18.040 chemicals to do this kind of siege engine, and you 0:24:18.080 --> 0:24:20.800 could also just build this thing when you needed it. 0:24:20.840 --> 0:24:25.200 In fact, most siege engines were constructed at site where 0:24:25.240 --> 0:24:28.040 the siege was happening, because they were so big and 0:24:28.080 --> 0:24:31.879 heavy that moving them from one place across country to 0:24:31.920 --> 0:24:35.040 another place was not really practical. So usually we just 0:24:35.040 --> 0:24:38.239 go to the closest forest, cut down some logs, and 0:24:38.320 --> 0:24:41.760 have some workers start to build siege engines right there 0:24:41.760 --> 0:24:44.000 on site, wheel them in a place so that they're 0:24:44.000 --> 0:24:45.959