WEBVTT - TechStuff Dives into Submarines 0:00:04.240 --> 0:00:07.240 Welcome to Tech Stuff, a production of I Heart Radios, 0:00:07.320 --> 0:00:14.000 How Stuff Works. Hey there, and welcome to tech Stuff. 0:00:14.120 --> 0:00:18.200 I'm your host, Jonathan Strickland. I'm an executive producer with 0:00:18.520 --> 0:00:20.920 I Heart Radio and How Stuff Works and a lot 0:00:20.920 --> 0:00:26.560 of all things tech and over on Twitter, a listener 0:00:26.640 --> 0:00:30.000 named Steve sent me a message asking me to do 0:00:30.120 --> 0:00:34.480 an episode about submarines, and I was sure I had 0:00:34.560 --> 0:00:38.160 done a full episode about submarines before, But then after 0:00:38.280 --> 0:00:41.120 I searched the archives, the best I could find was 0:00:41.520 --> 0:00:45.320 an episode I did with Scott Benjamin about personal submarines 0:00:45.360 --> 0:00:49.680 that was more about the expensive and frankly dangerous toys 0:00:50.280 --> 0:00:53.320 of people who have way more money than they have 0:00:53.479 --> 0:00:57.080 self preservation instincts. So in this episode, I'm really going 0:00:57.120 --> 0:01:01.320 to cover the history of submarines and how they work. Actually, 0:01:01.360 --> 0:01:03.760 this is the first of a couple of episodes because 0:01:03.760 --> 0:01:06.680 the history is pretty long, and while I could have 0:01:06.760 --> 0:01:10.600 summarized the early history of submarines, I find that that 0:01:10.640 --> 0:01:14.000 development is really fascinating. I mean, you think about what 0:01:14.040 --> 0:01:19.800 it would take to risk everything by building a contraption 0:01:20.040 --> 0:01:23.200 that can travel under the water where and you may 0:01:23.240 --> 0:01:28.440 not know this, people can't normally breathe so we're gonna 0:01:28.480 --> 0:01:31.760 look at the early history of submarines, not even getting 0:01:31.760 --> 0:01:36.160 into the twentieth century in this episode. Spoiler alert. So 0:01:36.680 --> 0:01:39.440 part of what makes this a fun topic to research 0:01:39.520 --> 0:01:42.039 is that you really get to see when humans first 0:01:42.040 --> 0:01:47.000 began to suss out why stuff floats or sinks. Archimedes 0:01:47.160 --> 0:01:49.800 or Archie as I like to call him, wrote down 0:01:50.080 --> 0:01:52.840 the earliest account of why this is at least the 0:01:52.880 --> 0:01:56.080 earliest that we know of. There may have been earlier accounts, 0:01:56.200 --> 0:01:58.320 but this is the one that we know about. He 0:01:58.400 --> 0:02:03.040 described a force of a body partially submerged in a 0:02:03.120 --> 0:02:07.160 fluid that would then push that body upward. And the 0:02:07.200 --> 0:02:09.840 story goes that he figured this out while taking a bath, 0:02:09.960 --> 0:02:12.880 that he figured out that this force that would hold 0:02:12.919 --> 0:02:16.320 a body up in water. Uh, was something that came 0:02:16.320 --> 0:02:19.720 to him while he was he himself was actually in water. 0:02:20.639 --> 0:02:24.680 And one of the principles that describes this force, it's 0:02:24.720 --> 0:02:29.640 called bullyancy. Essentially, it's saying that the amount of force 0:02:29.800 --> 0:02:34.320 that is exerted on the submerged object is equal to 0:02:34.400 --> 0:02:39.200 the weight of the water that the object is displacing. Now, 0:02:39.360 --> 0:02:42.440 as a kid, I remember being a bit confused about 0:02:42.480 --> 0:02:45.360 this concept because you take a look at stuff around you, 0:02:45.400 --> 0:02:47.440 and you see what floats or sinks, and it it's 0:02:47.480 --> 0:02:53.040 not always you know, uh, intuitive to a child, or, 0:02:53.639 --> 0:02:55.800 if I'm going to be honest, to a young adult. 0:02:55.960 --> 0:02:58.480 It took me a while to grasp this thing because 0:02:58.520 --> 0:03:02.080 you know, like rocks sing in the water, right, rock sinks. 0:03:02.120 --> 0:03:05.920 But then you have giant ships, like enormous, huge ships 0:03:05.960 --> 0:03:10.600 that are clearly much heavier than rocks are, and those float. Now, 0:03:10.600 --> 0:03:13.760 in my kid brain, I couldn't reconcile this. I mean, 0:03:14.040 --> 0:03:16.960 clearly it had to be the weight of stuff that 0:03:17.120 --> 0:03:20.519 determined whether or not it sank. Right, obviously, now that's 0:03:20.560 --> 0:03:23.680 not correct, But it took a while before my brain 0:03:23.720 --> 0:03:27.360 could wrap itself around the reasons why. So, the reason 0:03:28.000 --> 0:03:33.639 is all about displacement water displacement. If the object displaces 0:03:33.800 --> 0:03:36.600 enough water so that the weight of the water it 0:03:36.680 --> 0:03:41.000 displaces is greater than the weight of the object, then 0:03:41.040 --> 0:03:44.000 the object will float. If the object displaces too little 0:03:44.040 --> 0:03:47.560 water so that the displaced water weighs less than the 0:03:47.560 --> 0:03:50.400 weight of the object, then it will sink. And really 0:03:50.400 --> 0:03:53.280 it comes down to density, not so much weight, but 0:03:53.360 --> 0:03:56.440 really density. So if the density of the object is 0:03:56.520 --> 0:03:59.080 less than that of water, it will float. If it 0:03:59.160 --> 0:04:02.120 is greater than water, it will sink. And density and 0:04:02.160 --> 0:04:04.880 mass are pretty easy to confuse. For goofballs like me. 0:04:05.480 --> 0:04:08.920 Mass is how much stuff an object has. You know 0:04:08.960 --> 0:04:12.520 how much stuff is to that particular thing. A chair 0:04:12.600 --> 0:04:16.880 has a certain mass, but that's just part of an 0:04:16.920 --> 0:04:20.039 object's physical features. You also have to take into account 0:04:20.120 --> 0:04:23.120 the density, which is what you can think of as 0:04:23.120 --> 0:04:27.720 the distribution of mass within an object. So a dense 0:04:27.839 --> 0:04:30.680 object is going to have its mass packed in more 0:04:30.760 --> 0:04:34.760 tightly than a less dense object of the same size. 0:04:35.080 --> 0:04:37.240 So you have to think about the size, shape, and 0:04:37.520 --> 0:04:39.680 mass of a thing before you'll know whether it will 0:04:39.720 --> 0:04:43.880 displace enough water to keep it afloat. Our comedees actually 0:04:43.960 --> 0:04:47.160 used water displacement to determine density as well. So the 0:04:47.200 --> 0:04:51.200 basic formula for density is you take an objects mass 0:04:51.279 --> 0:04:54.279 and you divide it by the objects volume, And you 0:04:54.279 --> 0:04:56.960 would use scales to determine an object's mass, right, you 0:04:56.960 --> 0:05:01.120 would have weights that you knew equalled out to a 0:05:01.160 --> 0:05:04.400 specific amount of mass, like a kilogram weight, for example, 0:05:04.800 --> 0:05:07.080 and you would weigh an object against that. But unless 0:05:07.120 --> 0:05:10.120 the object is of a standard sort of shape, like 0:05:10.240 --> 0:05:13.200 you know, a box, you might not have a neat 0:05:13.320 --> 0:05:16.520 and nifty formula you could use to describe its volume. 0:05:16.720 --> 0:05:19.200 You know, if it's an irregular shape, it's tricky. How 0:05:19.200 --> 0:05:22.760 do you figure out the volume of an irregularly shaped object. Well, 0:05:23.080 --> 0:05:26.080 you could use water, and that's because we know that 0:05:26.200 --> 0:05:31.520 water behaves with displacement in a very consistent way under 0:05:31.560 --> 0:05:37.520 specific conditions. So one millilet of water will occupy one 0:05:37.720 --> 0:05:42.000 cubic centimeter of space. And this is specifically when water 0:05:42.080 --> 0:05:45.080 is at standard conditions, which a standard temperature is zero 0:05:45.120 --> 0:05:49.520 degrees celsius and standard pressure would be at one atmosphere. 0:05:49.800 --> 0:05:52.640 And that's because we want to make sure we're using 0:05:52.680 --> 0:05:56.719 standard conditions because you know, obviously water molecules will move 0:05:56.880 --> 0:05:59.359 apart as you heat them up, so you'll get some 0:05:59.400 --> 0:06:04.680 expansion and more air pressure adds compressive elements. Although to 0:06:04.760 --> 0:06:08.920 be fair, water is extremely difficult to compress and that 0:06:08.960 --> 0:06:15.400 would change the measurements slightly. So under standard conditions we 0:06:15.480 --> 0:06:19.640 have this idea that water occupies one million leader or 0:06:19.680 --> 0:06:22.039 one million eader of water. Rather we'll occupy one cubic 0:06:22.080 --> 0:06:26.960 centimeter space. So an object completely submerged in water displaces 0:06:27.120 --> 0:06:30.960 or offsets a volume of water equal to the volume 0:06:31.040 --> 0:06:33.440 of the object. So if you put an object in 0:06:33.600 --> 0:06:37.760 water at standard conditions and you have a little you know, 0:06:38.279 --> 0:06:41.119 measuring stick there that lets you read how much water 0:06:41.360 --> 0:06:43.640 has been displaced, and you see that the water has 0:06:43.680 --> 0:06:47.240 been displaced by a hundred millilaters, that would mean that 0:06:47.279 --> 0:06:49.560 the object you put in the water has a volume 0:06:49.600 --> 0:06:53.600 of one hundred cubic centimeters. One million leader equals one 0:06:53.640 --> 0:06:56.960 cubic centimeter. So then you would take the objects mass, 0:06:57.520 --> 0:07:00.440 you would divide it by that one dred cubic center meters, 0:07:00.880 --> 0:07:04.599 and that would tell you what the object's density is. Now, 0:07:04.640 --> 0:07:08.880 water's density at twenty degrees celsius is one gram per 0:07:08.960 --> 0:07:12.760 cubic centimeter, So if the object's density is less than that, 0:07:13.240 --> 0:07:16.600 it will float. If it's greater than that, it'll sink. 0:07:17.240 --> 0:07:20.320 This is why giant warships made out of metal can 0:07:20.320 --> 0:07:23.440 cruise along the waves, and while they weigh a lot, 0:07:23.520 --> 0:07:28.120 the water they displace has much greater density, so the 0:07:28.160 --> 0:07:30.560 boats will stay afloat. But what if you designed a 0:07:30.640 --> 0:07:33.560 vessel that could travel under the water, or better yet, 0:07:34.000 --> 0:07:36.720 you designed the vessel that could have some sort of 0:07:36.960 --> 0:07:40.680 control mechanism to allow it to either float or dive 0:07:40.920 --> 0:07:44.520 under the water. On top of that, there's another pesky 0:07:44.640 --> 0:07:47.440 problem to work out besides figuring out how to get 0:07:47.720 --> 0:07:51.640 a vessel to go above or below the waves. Assuming 0:07:52.120 --> 0:07:55.320 this vessel is also meant to hold people, there has 0:07:55.360 --> 0:07:57.680 to be some sort of method for getting air to 0:07:57.760 --> 0:08:00.200 the people inside, as we don't tend to funk action 0:08:00.320 --> 0:08:03.120 too well if we can't breathe, So that also was 0:08:03.160 --> 0:08:06.360 a problem that had to be solved now. Since ancient times, 0:08:06.640 --> 0:08:09.880 we knew we could bring air down with us under water, 0:08:10.600 --> 0:08:13.520 but that air would only last a short while before 0:08:13.560 --> 0:08:16.440 the oxygen levels were too low to be useful and 0:08:16.480 --> 0:08:20.000 we would asphyxiate. We didn't have a grasp on oxygen 0:08:20.080 --> 0:08:22.600 and carbon dioxide just yet, but we did know that 0:08:22.720 --> 0:08:25.840 you couldn't just keep breathing the same air indefinitely. Eventually 0:08:25.880 --> 0:08:29.600 you would have exhausted all the breathable air and you 0:08:29.640 --> 0:08:35.080 would need to resurface. Aristotle wrote about diving bells, which 0:08:35.080 --> 0:08:38.400 are containers that could be lowered with the open side 0:08:38.440 --> 0:08:41.360 of the container facing the floor of the ocean or 0:08:41.360 --> 0:08:44.719 the lake or river or whatever, and they could be 0:08:44.760 --> 0:08:47.960 dense enough to sink even with the added buoyancy of 0:08:48.000 --> 0:08:52.360 the captured air inside the container, and water pressure would 0:08:52.440 --> 0:08:55.920 keep the air from escaping the container, and he wrote, quote, 0:08:56.280 --> 0:09:00.360 they enable the divers to respire equally well by letting 0:09:00.360 --> 0:09:03.160 down a cauldron, for this does not fill with water, 0:09:03.400 --> 0:09:06.440 but retains the air in the quote, So essentially a 0:09:06.480 --> 0:09:09.600 diving bell. And that was way back in the fourth 0:09:09.640 --> 0:09:12.520 century b c. But that was also before we had 0:09:12.520 --> 0:09:15.440 susced out a way to replenish the air in the 0:09:15.480 --> 0:09:18.600 diving bell. So while you could use it to go underwater, 0:09:18.880 --> 0:09:20.760 you couldn't hang out for very long before you had 0:09:20.800 --> 0:09:23.240 consumed all the breathable air and you needed to resurface. 0:09:23.640 --> 0:09:26.840 So another problem is that water pressure that I just 0:09:26.880 --> 0:09:29.960 talked about. It would compress the air inside a diving bell, 0:09:30.200 --> 0:09:32.680 so the air would take up less space inside the bell, 0:09:33.040 --> 0:09:35.520 and the bottom of the bell, assuming you're looking at 0:09:35.559 --> 0:09:38.840 it with the bottom being the open side, would fill 0:09:38.920 --> 0:09:40.800 a little bit with water. The water would come up 0:09:40.800 --> 0:09:43.800 a little bit along the inside of the container, which 0:09:43.880 --> 0:09:46.360 means you have a reduced work area as well a 0:09:46.440 --> 0:09:50.360 reduced amount of useful area where you, as a person 0:09:50.880 --> 0:09:53.920 could inhabit and still breathe. One way to fix that 0:09:54.320 --> 0:09:58.480 would be to have a supply of pressurized air continue 0:09:58.520 --> 0:10:01.000 to come down into the bell. But it would take 0:10:01.080 --> 0:10:04.840 centuries to get that point. If you just included, say 0:10:04.960 --> 0:10:08.240 a breathing tube from the bell to the surface, well 0:10:08.320 --> 0:10:10.560 that wouldn't do any good at all. The water would 0:10:10.600 --> 0:10:13.400 just go right up the bell and up the tube 0:10:13.600 --> 0:10:16.280 a great deal. It's like if you put a straw 0:10:16.760 --> 0:10:21.160 inside a glass of liquid. You know, unless you cap 0:10:21.240 --> 0:10:24.200 the end of the straw, the liquid goes up the straw. 0:10:24.720 --> 0:10:27.440 You don't have any way of pressurizing it to keep 0:10:27.520 --> 0:10:30.760 the water from coming in. So you would have to 0:10:30.800 --> 0:10:33.360 have this pressurized system and it would take hundreds of 0:10:33.440 --> 0:10:36.800 years to get to that point. So when it comes 0:10:36.800 --> 0:10:42.239 to getting really great details about the origin of submarines, 0:10:42.920 --> 0:10:47.520 we hit some pretty big snags. There are reports about them, 0:10:47.559 --> 0:10:49.960 but they aren't necessarily the most reliable. A lot of 0:10:49.960 --> 0:10:52.760 them are second or third hand reports, and they don't 0:10:52.800 --> 0:10:55.480 tend to have a whole lot of information about what 0:10:55.720 --> 0:10:59.959 exactly happened or how it happened. But the general can 0:11:00.080 --> 0:11:03.440 census is that a design for what would be the 0:11:03.520 --> 0:11:06.880 first submarine that we have on record came from a 0:11:06.920 --> 0:11:12.160 guy named William Bourne born was an English mathematician way 0:11:12.200 --> 0:11:15.240 back in the sixteenth century, and the record of his 0:11:15.320 --> 0:11:19.079 design dates to fifteen seventy eight, so just to give 0:11:19.080 --> 0:11:22.000 you a little bit of context, at that time, England 0:11:22.120 --> 0:11:26.040 was ruled by Queen Elizabeth the First and Shakespeare was 0:11:26.080 --> 0:11:30.200 just fourteen years old. Born's design called for a totally 0:11:30.360 --> 0:11:35.040 enclosed wooden boat, and then covering this wooden boat would 0:11:35.040 --> 0:11:38.960 be oiled or greased leather that would help keep the 0:11:39.000 --> 0:11:43.760 vessel water tight in order to reduce buoyancy. Borne's proposal 0:11:43.840 --> 0:11:47.440 was to have hand cranked vices that connected to the 0:11:47.480 --> 0:11:51.240 interior of the boat's hull. Now, in some descriptions that 0:11:51.280 --> 0:11:54.200 I've read, it said that Borne intended to use the 0:11:54.320 --> 0:11:57.560 vices to pull the sides in a little bit like 0:11:57.600 --> 0:12:00.680 you're you're squeezing the boat from the in side, pulling 0:12:00.720 --> 0:12:05.080 the inner walls inward and reducing the overall volume of 0:12:05.120 --> 0:12:09.680 the boat, thus increasing your density. An illustration seems to 0:12:09.720 --> 0:12:12.480 indicate that the idea was actually to have an inner 0:12:12.559 --> 0:12:18.400 chamber inside this vessel, and that uh the inner chamber, 0:12:18.440 --> 0:12:22.160 the innermost chamber where a person would be, would be waterproofed, 0:12:22.600 --> 0:12:27.600 and then you would have space between this inner chamber 0:12:27.640 --> 0:12:30.559 and these the hull or the outer sides of the boat, 0:12:30.920 --> 0:12:34.240 So you would have this secondary chamber on either side 0:12:34.840 --> 0:12:37.960 of the place where the operator would sit, and so 0:12:38.080 --> 0:12:42.959 the visas would actually pull the boat's sections of whole 0:12:43.160 --> 0:12:47.120 inward and allow those parts of the boat to be 0:12:47.240 --> 0:12:51.840 flooded with water. So you're essentially pulling open almost like 0:12:51.880 --> 0:12:55.640 a trap door. You're pulling in sides of the hull 0:12:55.679 --> 0:13:00.680 of the boat. Water rushes in into a watertight section 0:13:01.400 --> 0:13:05.080 that it surrounds the inner chamber where the operator sits, 0:13:05.640 --> 0:13:10.120 and that would increase the density of the overall vessel. 0:13:10.600 --> 0:13:14.160 That's what would allow you to sink beneath the waves. 0:13:15.480 --> 0:13:17.959 If that's the case, I'm not sure what the plan 0:13:18.240 --> 0:13:21.880 was to return buoyancy to the boat, because you would 0:13:21.920 --> 0:13:24.880 need to have some way to purge the water out 0:13:25.559 --> 0:13:28.200 of the space between the whole and the inner chamber 0:13:28.679 --> 0:13:31.560 while sealing the boat closed. Again, you have to have 0:13:31.559 --> 0:13:33.760 some way to force the water back out, otherwise you're 0:13:33.800 --> 0:13:36.880 not gonna You're not going to decrease the density and 0:13:36.920 --> 0:13:39.880 thus increase the buoyancy and be able to rise back 0:13:39.960 --> 0:13:42.720 up above the waves. And maybe that's why Bourne never 0:13:42.760 --> 0:13:45.880 made the darn thing as far as we can tell. Instead, 0:13:46.040 --> 0:13:49.240 his design would remain an intriguing thought experiment for the 0:13:49.280 --> 0:13:52.640 time being. Skip ahead of Monarch to the time of 0:13:52.760 --> 0:13:55.960 James the First of England, and we do get to 0:13:56.040 --> 0:13:59.440 what most people consider to be the first submarine. A 0:13:59.559 --> 0:14:04.720 Dutch inventor named Cornelius van Drebble reportedly built a submarine, 0:14:04.720 --> 0:14:09.079 which he called a diving boat in the early sixteen twenties. 0:14:09.640 --> 0:14:14.080 Like Bourns proposed craft, Drebble's submarine was made of wood 0:14:14.120 --> 0:14:18.120 and coated with greased leather. Propulsion came from ores that 0:14:18.240 --> 0:14:21.680 extended out the sides of the vessel. These oars, you know, 0:14:21.920 --> 0:14:25.800 the parts where the ore extended out from inside the boat. 0:14:26.160 --> 0:14:28.840 Those had to be coated with flaps of leather to 0:14:28.960 --> 0:14:32.880 create a waterproof seal, because otherwise they're going to get 0:14:32.880 --> 0:14:37.800 water coming into your submarine. That's bad business. According to accounts, 0:14:37.840 --> 0:14:40.400 it could dip as far as twelve or even fifteen 0:14:40.440 --> 0:14:43.960 feet beneath the surface of the water, and Drebble demonstrate 0:14:44.040 --> 0:14:48.120 the craft along the Thames River in London. Supposedly, even 0:14:48.240 --> 0:14:51.560 Jimmy the King took a ride at one point. Now, 0:14:51.600 --> 0:14:55.200 if Drebble made any detailed records of how this boat 0:14:55.240 --> 0:14:58.840 actually worked, they have long since been lost. To time, 0:14:59.120 --> 0:15:02.080 we're not entire really certain what mechanism he relied upon 0:15:02.400 --> 0:15:05.240 to get the boat to go underwater. Some people have 0:15:05.320 --> 0:15:09.080 suggested that the boat had some form of ballast barrels 0:15:09.240 --> 0:15:12.800 or bladders that could be opened which would allow water 0:15:12.880 --> 0:15:16.080 to come inside of them, increasing the overall density of 0:15:16.120 --> 0:15:18.800 the boat, and this causing it to sink beneath the waves, 0:15:19.080 --> 0:15:21.720 though I've not seen any description of how the vessel 0:15:21.760 --> 0:15:26.160 would then expel the water to regain buoyancy. Uh. In 0:15:26.360 --> 0:15:29.640 my just jettison the ballast, in which case then it 0:15:29.640 --> 0:15:32.800 would rise up it's buoyancy would be returned. The earliest 0:15:32.840 --> 0:15:35.840 records I can find of any kind of ballast system 0:15:35.880 --> 0:15:41.640 actually comes two hundred years after this particular example. Others 0:15:41.800 --> 0:15:45.880 suggest that perhaps the sloped shape of the bow that's 0:15:45.880 --> 0:15:48.760 the front part of the boat acted as a sort 0:15:48.800 --> 0:15:52.280 of reverse airplane wing, that when the boat began to 0:15:52.360 --> 0:15:55.880 move forward, the slope would cause the water to flow 0:15:56.040 --> 0:15:58.320 over the top of the boat, and that would push 0:15:58.400 --> 0:16:01.640 the boat downward into the wall watter uh, And that 0:16:01.840 --> 0:16:04.560 maybe with a system of weights could have added a 0:16:04.600 --> 0:16:08.080 bit more downward force. I find that particular idea, the 0:16:08.160 --> 0:16:12.080 idea of forward motion creating the downward force to allow 0:16:12.200 --> 0:16:16.240 the boat to dive to be a little unlikely, simply 0:16:16.280 --> 0:16:19.640 because I don't think you'd be able to go very 0:16:19.800 --> 0:16:23.320 fast with oars. I don't think you could row fast 0:16:23.440 --> 0:16:28.600 enough to make that downward motion, uh strong enough to 0:16:28.720 --> 0:16:31.560 keep the boat underwater. You might bob a bit in 0:16:31.640 --> 0:16:33.920 the Thames, but I don't think you would be able 0:16:33.960 --> 0:16:37.480 to go twelve to fifteen feet beneath the surface. That's 0:16:37.520 --> 0:16:40.160 just my own gut feeling there, because I don't think 0:16:40.160 --> 0:16:42.880 you could get up the speed necessary to maintain that. 0:16:43.600 --> 0:16:46.000 But we just don't really know for sure what the 0:16:46.000 --> 0:16:49.800 mechanism was. Drebble made sure that the vessel had a 0:16:49.800 --> 0:16:53.440 study supply of air by attaching to air hoses to 0:16:53.480 --> 0:16:56.000 the boat, and the other ends of the hoses were 0:16:56.000 --> 0:16:58.320 attached to floats that would drift on the surface of 0:16:58.320 --> 0:17:02.240 the Thames above the boat. Now, I'm assuming that there 0:17:02.280 --> 0:17:05.240 must have been some method of pumping the air down 0:17:05.480 --> 0:17:09.920 into the boat, because otherwise you would have a problem. See, 0:17:09.960 --> 0:17:14.080 carbon dioxide is denser than air, which means you need 0:17:14.119 --> 0:17:17.080 a way to force breathable air down the hose to 0:17:17.160 --> 0:17:21.280 the interior of the submarine. Otherwise it would become saturated 0:17:21.320 --> 0:17:24.720 with C O two and you would eventually suffocate. This 0:17:24.840 --> 0:17:29.800 was something an inventor named de Lorena, an Italian inventor, 0:17:29.840 --> 0:17:32.240 had figured out way back in fift thirty five. He 0:17:32.320 --> 0:17:36.800 made a diving bell with an apparatus that would replenish pressurized, 0:17:36.960 --> 0:17:41.440 breathable air into the bell. Though he took the secret 0:17:41.760 --> 0:17:45.520 of that invention to the grave. One other person reportedly 0:17:45.760 --> 0:17:48.440 understood how it worked, but had sworn an oath never 0:17:48.520 --> 0:17:53.040 to reveal it. So we don't know the precise methodology 0:17:53.200 --> 0:17:56.680 used in that case either. Now, I'm sure it got 0:17:56.720 --> 0:18:00.439 stuffy and humid inside Drebble's boat, but at least you 0:18:00.440 --> 0:18:02.720 could get some air down there, and the crew wouldn't 0:18:02.760 --> 0:18:07.240 automatically just die of asphyxiation. So the submarine as a working, 0:18:07.440 --> 0:18:11.800 though primitive concept, dates back about five years, and I'm 0:18:11.800 --> 0:18:13.679 sure it will come as a shock to learn that 0:18:13.760 --> 0:18:17.320 since then we've made a few advancements. When we come back, 0:18:17.480 --> 0:18:19.600 I'll talk a bit more about some of the earliest 0:18:19.720 --> 0:18:23.600 subs and technology that made them work. But first let's 0:18:23.600 --> 0:18:35.200 take a quick break. Okay, So, by the seventeen hundreds, 0:18:35.280 --> 0:18:40.120 several inventors had experimented with different designs for submersible vehicles, 0:18:40.440 --> 0:18:44.240 and they weren't really practical craft just yet, though the 0:18:44.320 --> 0:18:48.800 potential military applications were immediately apparent. So this was during 0:18:48.800 --> 0:18:52.560 the age when countries were imposing their will on others, 0:18:52.600 --> 0:18:58.280 primarily through naval supremacy. Countries like Spain and England in 0:18:58.320 --> 0:19:01.600 particular were known for doing this, and a common tactic 0:19:02.040 --> 0:19:05.639 was to create a naval blockade around a port city 0:19:05.960 --> 0:19:09.399 to prevent ships from leaving or arriving at that port city. 0:19:09.760 --> 0:19:14.000 Creating a submersible that could secretly approach a blockade and 0:19:14.040 --> 0:19:17.280 disrupt it, typically through the use of explosives that some 0:19:17.560 --> 0:19:20.879 poor submarner would have to try and attach to those 0:19:20.880 --> 0:19:25.120 boats was an obvious application for a submarine. It would 0:19:25.119 --> 0:19:30.480 be an incredibly useful war tool. In se we get 0:19:30.480 --> 0:19:35.280 the earliest published account of a ballast bladder, which some 0:19:35.480 --> 0:19:39.680 unknown inventor suggested using bags made out of goat skin 0:19:39.800 --> 0:19:42.840 to take in water so that submarine could dive below 0:19:42.880 --> 0:19:45.720 the waves, and the bags would have a twisting rod 0:19:45.960 --> 0:19:49.280 attached to them that would extend into the interior of 0:19:49.320 --> 0:19:52.840 the submarine itself, so the submarner could grab all of 0:19:52.880 --> 0:19:55.600 the rod and give it a good twist, and that 0:19:55.680 --> 0:19:58.680 in turn would twist the ballast bag and that would 0:19:58.680 --> 0:20:01.159 force water out of the ballast bag. It would have 0:20:01.200 --> 0:20:03.800 a valve on the end of the bag so that 0:20:03.840 --> 0:20:06.480 the water couldn't just come right back in, and that 0:20:06.520 --> 0:20:10.080 would decrease the vessel's density and allow it to surface. 0:20:10.480 --> 0:20:13.919 This was a predecessor for ballast tanks essentially do the 0:20:13.960 --> 0:20:17.320 same thing, though you don't typically have to hand operate 0:20:17.400 --> 0:20:20.560 them these days. A few decades later, we have the 0:20:20.600 --> 0:20:24.280 first use of a submarine in war. That was the 0:20:24.359 --> 0:20:27.879 American Revolutionary War. There was actually a submarine in the 0:20:27.920 --> 0:20:32.320 American Revolutionary War. The submarine was called the Turtle. And 0:20:32.480 --> 0:20:36.159 this was a pretty modest submarine. It's not like the 0:20:36.240 --> 0:20:40.000 Red October or anything like that. It could hold precisely 0:20:40.320 --> 0:20:44.600 one person. It was the design of David Bushnell, a 0:20:44.600 --> 0:20:47.760 an engineering student who was studying at Yale at the time. 0:20:47.840 --> 0:20:50.760 He and his brother Ezra built the dang Durn thing. 0:20:51.200 --> 0:20:55.280 The Encyclopedia Britannica describes the shape of the submarine as 0:20:55.320 --> 0:21:00.159 a quote walnut standing on end end to quote. And 0:21:00.200 --> 0:21:04.600 if you see illustrations or the recreations of this particular submarine, 0:21:04.640 --> 0:21:06.520 you'll see exactly what they mean. It does kind of 0:21:06.560 --> 0:21:10.840 look like a sort of oval shaped submarine, large enough 0:21:10.880 --> 0:21:14.440 to hold a single person on the inside. Facing forward 0:21:14.880 --> 0:21:17.600 from the submarine, at least from the perspective of the pilot, 0:21:18.119 --> 0:21:21.600 would be the propulsion system, which was a screw propeller 0:21:22.080 --> 0:21:25.200 and it worked on as similar principle as the Archimedes 0:21:25.359 --> 0:21:28.119 screw pump, which was used to lift water from areas 0:21:28.119 --> 0:21:32.080 of low elevation to areas of high elevation. The submarine 0:21:32.160 --> 0:21:36.280 operator would crank a handle in order to turn this 0:21:36.480 --> 0:21:40.600 screw propeller, which would effectively pull the submarine through the water, 0:21:41.200 --> 0:21:45.280 and then with the other hand, the operator would control 0:21:45.359 --> 0:21:48.280 a rudder that is in the back of the vessel 0:21:48.520 --> 0:21:52.520 to provide the steering mechanism. The vessel also had a 0:21:52.560 --> 0:21:57.359 secondary screw propeller, one that was oriented vertically, which meant 0:21:57.640 --> 0:22:00.520 it was meant to help the submariner navigate critically through 0:22:00.560 --> 0:22:03.560 the water, So if you were to dive beneath the waves, 0:22:04.040 --> 0:22:08.000 you would use the vertical screw propeller to push you 0:22:08.080 --> 0:22:11.080 down further into the water or to pull you up 0:22:11.480 --> 0:22:15.520 to actually drive. The turtle had a chamber that would 0:22:15.520 --> 0:22:18.600 be flooded with opening a valve, and that would just 0:22:18.800 --> 0:22:21.160 decrease the ship's buoyancy, so it would start to sink 0:22:21.560 --> 0:22:25.320 uh to surface. The operator could work some pumps inside 0:22:25.320 --> 0:22:28.280 the turtle that would push this water back out of 0:22:28.320 --> 0:22:32.879 that chamber. It also had ballast, both inside and attached 0:22:33.000 --> 0:22:35.520 to the outside of the vessel that was used to 0:22:35.520 --> 0:22:38.000 make sure the craft would maintain the proper orientation in 0:22:38.040 --> 0:22:40.520 the water and not just you know, start flipping over 0:22:40.680 --> 0:22:43.480 tilting to the side, which would be disastrous to the operator. 0:22:43.880 --> 0:22:46.560 So the weights were really meant to make sure that 0:22:46.600 --> 0:22:51.640 it maintained that up down orientation. Air came in through 0:22:51.680 --> 0:22:55.879 a pair of snorkels, and the snoricles had lids that 0:22:55.920 --> 0:23:00.440 would close whenever the vessel were to go underwater. Windows 0:23:00.480 --> 0:23:04.240 on the hatch above the the operator would allow some 0:23:04.359 --> 0:23:08.760 light to come into the interior of the vessel, although 0:23:08.760 --> 0:23:12.359 it was meant primarily to be operated at night, and 0:23:12.400 --> 0:23:15.720 the design also meant that if you went underwater, you 0:23:15.720 --> 0:23:18.760 would have a limited supply of air because the snorkels 0:23:18.800 --> 0:23:21.000 now would be closed, and you would also have much 0:23:21.080 --> 0:23:25.840 less light to work from. The intent was to operate 0:23:25.880 --> 0:23:28.600 so that only the hatch would be above the surface 0:23:28.600 --> 0:23:31.640 of the water for most of a mission, so that 0:23:31.760 --> 0:23:33.600 the operator would still be able to get a look 0:23:33.640 --> 0:23:36.320 around seeing where they were in relation to a target. 0:23:36.880 --> 0:23:39.359 They would also be able to breathe because the snorkels 0:23:39.400 --> 0:23:42.640 would be exposed to the air, and then the operator 0:23:42.640 --> 0:23:47.680 would only dive with the submarine in order to avoid 0:23:47.720 --> 0:23:51.320 being seen or when it came time to actually attach 0:23:51.480 --> 0:23:55.919 an explosive device to the target. To do that, the 0:23:55.960 --> 0:23:59.040 ship had a drill that was also pointed up from 0:23:59.119 --> 0:24:02.280 the top of a turtle, and this was to drill 0:24:02.359 --> 0:24:05.880 a hole in a blockade ship, and then in that 0:24:05.920 --> 0:24:10.920 hole the operator could attach a line for a gunpowder charge. 0:24:11.200 --> 0:24:13.359 And this gunpowder charge was in the form of a 0:24:13.400 --> 0:24:17.600 mine with an ingenious clockwork fuse mechanism, which I'll describe 0:24:17.640 --> 0:24:23.200 in just a second. Now, Bushnell had already conducted experiments 0:24:23.200 --> 0:24:27.400 while at Yale to find ways to make gunpowder explode underwater, which, 0:24:27.400 --> 0:24:29.960