WEBVTT 00:00:10.899 --> 00:00:13.759 When you think of Archimedes' Eureka! moment, 00:00:13.759 --> 00:00:16.294 you probably think of this. 00:00:16.294 --> 00:00:19.998 As it turns out, it may have been more like this. 00:00:19.998 --> 00:00:25.457 In the third century BC, Hieron, king of the Sicilian city of Syracuse, 00:00:25.457 --> 00:00:26.907 chose Archimedes to supervise 00:00:26.907 --> 00:00:30.925 an engineering project of unprecedented scale. 00:00:30.925 --> 00:00:33.010 Hieron commissioned a sailing vessel 00:00:33.010 --> 00:00:37.219 50 times bigger than a standard ancient warship. 00:00:37.219 --> 00:00:39.759 Named the Syracusia after his city, 00:00:39.759 --> 00:00:42.745 Hieron wanted to construct the largest ship ever, 00:00:42.745 --> 00:00:45.443 which was destined to be given as a present 00:00:45.443 --> 00:00:48.334 for Egypt's ruler, Ptolemy. 00:00:48.334 --> 00:00:51.845 But could a boat the size of a palace possibly float? 00:00:51.845 --> 00:00:55.752 In Archimedes's day, no one had attempted anything like this. 00:00:55.752 --> 00:00:58.994 It was like asking, "Can a mountain fly?" 00:00:58.994 --> 00:01:01.895 King Hieron had a lot riding on that question. 00:01:01.895 --> 00:01:06.038 Hundreds of workmen were to labor for years on constructing the Syracusia 00:01:06.038 --> 00:01:09.728 out of beams of pine and fir from Mount Etna, 00:01:09.728 --> 00:01:11.820 ropes from hemp grown in Spain, 00:01:11.820 --> 00:01:14.040 and pitch from France. 00:01:14.040 --> 00:01:17.379 The top deck, on which eight watchtowers were to stand, 00:01:17.379 --> 00:01:19.621 was to be supported not by columns, 00:01:19.621 --> 00:01:25.506 but by vast wooden images of Atlas holding the world on his shoulders. 00:01:25.506 --> 00:01:27.053 On the ship's bow, 00:01:27.053 --> 00:01:33.469 a massive catapult would be able to fire 180 pound stone missles. 00:01:33.469 --> 00:01:35.233 For the enjoyment of its passengers, 00:01:35.233 --> 00:01:38.220 the ship was to feature a flower-lined promenade, 00:01:38.220 --> 00:01:40.121 a sheltered swimming pool, 00:01:40.121 --> 00:01:42.791 and bathhouse with heated water, 00:01:42.791 --> 00:01:46.350 a library filled with books and statues, 00:01:46.350 --> 00:01:48.954 a temple to the goddess Aphrodite, 00:01:48.954 --> 00:01:52.069 and a gymnasium. 00:01:52.069 --> 00:01:54.896 And just to make things more difficult for Archimedes, 00:01:54.896 --> 00:01:58.661 Hieron intended to pack the vessel full of cargo: 00:01:58.661 --> 00:02:00.803 400 tons of grain, 00:02:00.803 --> 00:02:03.470 10,000 jars of pickled fish, 00:02:03.470 --> 00:02:06.074 74 tons of drinking water, 00:02:06.074 --> 00:02:09.199 and 600 tons of wool. 00:02:09.199 --> 00:02:12.982 It would have carried well over a thousand people on board, 00:02:12.982 --> 00:02:15.393 including 600 soldiers. 00:02:15.393 --> 00:02:19.773 And it housed 20 horses in separate stalls. 00:02:19.773 --> 00:02:21.430 To build something of this scale, 00:02:21.430 --> 00:02:24.132 only for that to sink on its maiden voyage, 00:02:24.132 --> 00:02:26.107 well let's just say that failure 00:02:26.107 --> 00:02:29.432 wouldn't have been a pleasant option for Archimedes. 00:02:29.432 --> 00:02:32.614 So he took on the problem: will it sink? 00:02:32.614 --> 00:02:34.929 Perhaps he was sitting in the bathhouse one day, 00:02:34.929 --> 00:02:37.853 wondering how a heavy bathtub can float, 00:02:37.853 --> 00:02:40.324 when inspiration came to him. 00:02:40.324 --> 00:02:44.952 An object partially immersed in a fluid is buoyed up by a force 00:02:44.952 --> 00:02:49.711 equal to the weight of the fluid displaced by the object. 00:02:49.711 --> 00:02:55.747 In other words, if a 2,000 ton Syracusia displaced exactly 2,000 tons of water, 00:02:55.747 --> 00:02:58.243 it would just barely float. 00:02:58.243 --> 00:03:02.469 If it displaced 4,000 tons of water, it would float with no problem. 00:03:02.469 --> 00:03:05.895 Of course, if it only displaced 1,000 tons of water, 00:03:05.895 --> 00:03:09.752 well, Hieron wouldn't be too happy. 00:03:09.752 --> 00:03:12.644 This is the law of buoyancy, 00:03:12.644 --> 00:03:16.085 and engineers still call it Archimedes' principle. 00:03:16.085 --> 00:03:20.932 It explains why a steel supertanker can float as easily as a wooden rowboat, 00:03:20.932 --> 00:03:22.636 or a bathtub. 00:03:22.636 --> 00:03:25.780 If the weight of water displaced by the vessel below the keel 00:03:25.780 --> 00:03:28.088 is equivalent to the vessel's weight, 00:03:28.088 --> 00:03:32.425 whatever is above the keel will remain afloat above the waterline. 00:03:32.425 --> 00:03:36.441 This sounds a lot like another story involving Archimedes and a bathtub, 00:03:36.441 --> 00:03:39.691 and its possible that's because they're actually the same story, 00:03:39.691 --> 00:03:42.253 twisted by the vagueries of history. 00:03:42.253 --> 00:03:47.131 The classical story of Archimedes' Eureka! and subsequent streak through the streets 00:03:47.131 --> 00:03:50.767 centers around a crown, or corona in Latin. 00:03:50.767 --> 00:03:56.771 At the core of the Syracusia story is a keel, or korone in Greek. 00:03:56.771 --> 00:03:58.951 Could one have been mixed up for the other? 00:03:58.951 --> 00:04:00.659 We may never know. 00:04:00.659 --> 00:04:05.507 On the day the Syracusia arrived in Egypt on its first and only voyage, 00:04:05.507 --> 00:04:09.333 we can only imagine how residents of Alexandria thronged the harbor 00:04:09.333 --> 00:04:14.084 to marvel at the arrival of this majestic, floating castle. 00:04:14.084 --> 00:04:18.515 This extraordinary vessel was the Titanic of the ancient world, 00:04:18.515 --> 00:04:23.240 except without the sinking, thanks to our pal, Archimedes.