1 00:00:04,040 --> 00:00:07,480 Speaker 1: Again in text with technology with tech Stuff from stuff 2 00:00:07,520 --> 00:00:14,240 Speaker 1: works dot com. Hey there, and welcome to tech Stuff. 3 00:00:14,280 --> 00:00:17,320 Speaker 1: I am your host, Jonathan Strickland. I'm an executive producer 4 00:00:17,360 --> 00:00:20,520 Speaker 1: here at how Stuff Works, and I love all things tech, 5 00:00:20,720 --> 00:00:24,640 Speaker 1: and today I wanted to talk about something that I've 6 00:00:24,640 --> 00:00:29,639 Speaker 1: always found interesting but also intimidating. A couple of years ago, 7 00:00:29,880 --> 00:00:32,640 Speaker 1: I traveled to Berlin, Germany to give a talk at 8 00:00:32,640 --> 00:00:36,200 Speaker 1: a conference. After my talk, a couple of really friendly 9 00:00:36,240 --> 00:00:38,839 Speaker 1: locals offered to give me a walking tour of Berlin, 10 00:00:38,960 --> 00:00:40,839 Speaker 1: and so we kind of set out to explore the 11 00:00:40,880 --> 00:00:44,120 Speaker 1: city and at one point we ducked into a luxury 12 00:00:44,240 --> 00:00:48,120 Speaker 1: clock shop and I got a nice explanation, half of 13 00:00:48,159 --> 00:00:50,760 Speaker 1: it in German, of the inner workings of some of 14 00:00:50,800 --> 00:00:53,720 Speaker 1: the more intricate clocks there. And it was really interesting 15 00:00:53,800 --> 00:00:58,160 Speaker 1: and incredible to see the workmanship that went into creating 16 00:00:58,160 --> 00:01:02,120 Speaker 1: these clocks. And I thought, well, it's about time to 17 00:01:02,160 --> 00:01:04,640 Speaker 1: talk about time, or rather to talk about how we 18 00:01:04,680 --> 00:01:08,120 Speaker 1: mark the passage of time. So today we're gonna talk 19 00:01:08,160 --> 00:01:11,000 Speaker 1: about clocks. Now, most of this episode I'm going to 20 00:01:11,080 --> 00:01:14,280 Speaker 1: focus on mechanical clocks, but you know me, I like 21 00:01:14,360 --> 00:01:17,480 Speaker 1: to talk about precursors. And history leading up to the 22 00:01:17,480 --> 00:01:21,280 Speaker 1: development of technology. And so we'll first take a quick 23 00:01:21,319 --> 00:01:24,760 Speaker 1: look back at some of the earliest timekeeping technologies before 24 00:01:24,880 --> 00:01:28,240 Speaker 1: the invention of the mechanical clock. So to count as 25 00:01:28,240 --> 00:01:32,240 Speaker 1: a clock, you really need two elements. The first is 26 00:01:32,280 --> 00:01:37,200 Speaker 1: some sort of consistent, regular action or process that gives 27 00:01:37,240 --> 00:01:40,680 Speaker 1: you the ability to mark off equal increments of time. 28 00:01:41,240 --> 00:01:43,600 Speaker 1: In theory, this could be something like the rate that 29 00:01:43,680 --> 00:01:46,240 Speaker 1: water drips out of a container, which is the basis 30 00:01:46,280 --> 00:01:49,960 Speaker 1: of many water clocks, or sands through an hourglass, so 31 00:01:50,080 --> 00:01:53,120 Speaker 1: are the days of our lives. But we'll talk more 32 00:01:53,200 --> 00:01:56,840 Speaker 1: about water clocks later. With mechanical clocks, it's the rate 33 00:01:56,920 --> 00:01:59,640 Speaker 1: at which parts move within the clock itself. In order 34 00:01:59,680 --> 00:02:01,240 Speaker 1: to keep time, you have to find a way to 35 00:02:01,360 --> 00:02:05,000 Speaker 1: regulate that so that it is consistent. So that's element 36 00:02:05,080 --> 00:02:07,440 Speaker 1: number one. The second element you need for a clock 37 00:02:07,560 --> 00:02:09,760 Speaker 1: is some sort of way to keep track of the 38 00:02:09,760 --> 00:02:12,520 Speaker 1: increments of time so that you know what time it is. 39 00:02:12,600 --> 00:02:14,919 Speaker 1: You need a way to be able to read the time. 40 00:02:15,560 --> 00:02:19,799 Speaker 1: So early clocks, some of the early mechanical clocks that 41 00:02:19,880 --> 00:02:23,160 Speaker 1: came out of Europe didn't have a dial or a 42 00:02:23,200 --> 00:02:26,800 Speaker 1: face or hands or anything like that. They were really 43 00:02:26,840 --> 00:02:30,160 Speaker 1: automated systems to chime bells, so it was the chime 44 00:02:30,160 --> 00:02:32,080 Speaker 1: of the bell that would indicate what the time was. 45 00:02:32,160 --> 00:02:35,280 Speaker 1: That was the best you could do. But later on 46 00:02:35,360 --> 00:02:38,239 Speaker 1: it would be a mechanical clock with a dial and 47 00:02:38,320 --> 00:02:41,679 Speaker 1: a face with hands on it, and that would be 48 00:02:42,080 --> 00:02:44,640 Speaker 1: the part that tells you what the time is. So 49 00:02:44,680 --> 00:02:46,640 Speaker 1: it's not enough that the clock keeps time. It also 50 00:02:46,720 --> 00:02:50,600 Speaker 1: has to communicate that or display it in some way. 51 00:02:50,840 --> 00:02:52,400 Speaker 1: So those are the two elements you need for it 52 00:02:52,440 --> 00:02:56,000 Speaker 1: to be a clock. Now, since ancient times, people have 53 00:02:56,080 --> 00:03:00,520 Speaker 1: found ways to mark the passing of time, everything from 54 00:03:00,600 --> 00:03:04,880 Speaker 1: various versions of calendars to massive structures that could tell 55 00:03:04,919 --> 00:03:08,480 Speaker 1: you all about when certain things are going to happen, 56 00:03:08,520 --> 00:03:10,920 Speaker 1: like equal n ox Is. I mean, you've heard about 57 00:03:11,639 --> 00:03:15,400 Speaker 1: structures like Stonehenge, But if you're talking about time, as 58 00:03:15,440 --> 00:03:18,359 Speaker 1: in dividing up the increments of a day, you kind 59 00:03:18,360 --> 00:03:21,480 Speaker 1: of have to look at the people's of Summer and 60 00:03:21,600 --> 00:03:25,880 Speaker 1: ancient Egypt and their use of sun dials. The most 61 00:03:25,880 --> 00:03:28,840 Speaker 1: primitive type of sun dial would be a stick stuck 62 00:03:28,840 --> 00:03:31,240 Speaker 1: in the ground, and you can mark the passing of 63 00:03:31,280 --> 00:03:34,120 Speaker 1: time by observing where the stick's shadow falls as the 64 00:03:34,120 --> 00:03:38,080 Speaker 1: sun's position overhead changes throughout the day. Sun dials tend 65 00:03:38,160 --> 00:03:40,840 Speaker 1: to be a bit more robust than a stick stuck 66 00:03:40,840 --> 00:03:43,360 Speaker 1: in the ground. The sun dials of ancient summer were 67 00:03:43,400 --> 00:03:46,000 Speaker 1: pretty much gone by the time historians got around to 68 00:03:46,080 --> 00:03:48,840 Speaker 1: documenting these kinds of things, but there were still some 69 00:03:49,120 --> 00:03:52,880 Speaker 1: that existed in Egypt. Now we know that the ones 70 00:03:52,920 --> 00:03:55,280 Speaker 1: in Egypt were predated by the ones that were in 71 00:03:55,360 --> 00:03:58,480 Speaker 1: sumer but we just don't have any examples of those 72 00:03:58,640 --> 00:04:02,160 Speaker 1: so UH. In Egypt you could find things like obelisks. 73 00:04:02,840 --> 00:04:05,560 Speaker 1: The obelisks dates to at least thirty d b c 74 00:04:05,800 --> 00:04:10,000 Speaker 1: e before Common era. The shadows cast by those structures 75 00:04:10,200 --> 00:04:13,200 Speaker 1: could help people mark the passing of time, and in fact, 76 00:04:13,280 --> 00:04:16,279 Speaker 1: you might end up seeing one that has markings on 77 00:04:16,400 --> 00:04:20,240 Speaker 1: the ground that indicates such. Now, both the Sumerians and 78 00:04:20,279 --> 00:04:23,720 Speaker 1: the Egyptians created divisions for daytime, similar to the way 79 00:04:23,760 --> 00:04:28,160 Speaker 1: we have ours. The Egyptians created ten segments of daytime 80 00:04:28,240 --> 00:04:31,640 Speaker 1: between UH and between two and four for night time, 81 00:04:31,680 --> 00:04:34,039 Speaker 1: but of course you couldn't track nighttime with a sun 82 00:04:34,080 --> 00:04:37,520 Speaker 1: dial because for a sundal to work, you kind of 83 00:04:37,560 --> 00:04:41,040 Speaker 1: need a sun and at nighttime that's in short supply. 84 00:04:41,880 --> 00:04:43,960 Speaker 1: The same was true on any days with whether that 85 00:04:43,960 --> 00:04:46,880 Speaker 1: would obscure the sun. Obviously, tracking time on those days 86 00:04:46,920 --> 00:04:50,560 Speaker 1: would become difficult, but on clear days you could track 87 00:04:50,640 --> 00:04:54,640 Speaker 1: the passing of time fairly well. The Egyptians would create 88 00:04:54,680 --> 00:04:57,000 Speaker 1: markings on the ground that would indicate the time of day, 89 00:04:57,040 --> 00:04:59,279 Speaker 1: so you'd see where the shadow falls. If it falls 90 00:04:59,520 --> 00:05:02,599 Speaker 1: in atcular section, then you know it's time for lunch 91 00:05:02,760 --> 00:05:05,440 Speaker 1: or I don't know. To listen to the New Bengals 92 00:05:05,720 --> 00:05:09,200 Speaker 1: single if the Earth's axis didn't have a tilt to 93 00:05:09,320 --> 00:05:12,120 Speaker 1: it relative to the position of the Sun, this would 94 00:05:12,120 --> 00:05:14,600 Speaker 1: be a consistent way to track the time of day. 95 00:05:14,800 --> 00:05:18,000 Speaker 1: But because of that tilt, during different parts of the year, 96 00:05:18,240 --> 00:05:20,800 Speaker 1: the sun will occupy a slightly different part of the sky. 97 00:05:21,560 --> 00:05:24,600 Speaker 1: This also depends upon where north or south of the 98 00:05:24,640 --> 00:05:26,880 Speaker 1: equator you are. If you're right, if you're very close 99 00:05:26,920 --> 00:05:31,080 Speaker 1: to the equator, the variation is slight, but the further 100 00:05:31,120 --> 00:05:33,440 Speaker 1: way you are from the equator, the greater the variation is. 101 00:05:33,680 --> 00:05:35,640 Speaker 1: And because of that tilt, during different parts of the year, 102 00:05:35,680 --> 00:05:38,400 Speaker 1: the sun will occupy those different areas of the sky, 103 00:05:38,520 --> 00:05:42,000 Speaker 1: meaning the shadow that it casts on the ground from 104 00:05:42,040 --> 00:05:44,000 Speaker 1: any object is going to be different at one time 105 00:05:44,040 --> 00:05:46,560 Speaker 1: of year than at a different time of year. The 106 00:05:46,560 --> 00:05:49,760 Speaker 1: Egyptians had all this sussed out, and they would include 107 00:05:49,760 --> 00:05:53,280 Speaker 1: indicators for the time of year so that timekeeping could 108 00:05:53,279 --> 00:05:56,440 Speaker 1: remain fairly accurate. And it was easy to see which 109 00:05:56,480 --> 00:05:58,760 Speaker 1: days were the longest and the shortest, because on the 110 00:05:58,800 --> 00:06:02,359 Speaker 1: longest day, the obelisk would cast a longer shadow because 111 00:06:02,360 --> 00:06:04,839 Speaker 1: the sun would appear lowest in the sky as it 112 00:06:04,880 --> 00:06:08,159 Speaker 1: crossed overhead. On the shortest day, the shadow would be 113 00:06:08,240 --> 00:06:11,920 Speaker 1: short as the Sun would pass closer to directly overhead. 114 00:06:12,080 --> 00:06:14,839 Speaker 1: So little indicators there that can tell you more about 115 00:06:14,880 --> 00:06:16,880 Speaker 1: the time of year. Now, the fact that the Earth 116 00:06:16,960 --> 00:06:20,719 Speaker 1: is round, sorry flat earther's it also meant that you 117 00:06:20,720 --> 00:06:23,560 Speaker 1: couldn't just design a universal sun dial that's going to 118 00:06:23,600 --> 00:06:26,839 Speaker 1: be accurate wherever you go all year round. As you 119 00:06:26,880 --> 00:06:28,960 Speaker 1: travel north or south, the angle of the Sun's light 120 00:06:29,040 --> 00:06:31,680 Speaker 1: hitting your sun dial changes, and so you have to 121 00:06:31,720 --> 00:06:34,600 Speaker 1: take that into account. A sun dial must be designed 122 00:06:34,600 --> 00:06:37,280 Speaker 1: for the specific location if you want the time markings 123 00:06:37,279 --> 00:06:40,520 Speaker 1: to be accurate throughout the year. The sun dial made 124 00:06:40,520 --> 00:06:44,080 Speaker 1: its way to Greece and from there pretty much everywhere else. 125 00:06:44,360 --> 00:06:48,280 Speaker 1: The Greeks created some pretty cool sun dials, including hemispherical 126 00:06:48,400 --> 00:06:51,559 Speaker 1: sun dials. Now, as this name suggests. These sun dials 127 00:06:51,640 --> 00:06:56,720 Speaker 1: used a hemispherical surface upon which shadows would fall. Typically 128 00:06:56,760 --> 00:06:59,240 Speaker 1: the surface kind of like a bowl that have been 129 00:06:59,279 --> 00:07:02,120 Speaker 1: cut in half or even quartered. So you had this 130 00:07:02,120 --> 00:07:06,000 Speaker 1: this little bowl shaped area, but not a not a 131 00:07:06,040 --> 00:07:09,760 Speaker 1: full bowl with lines on the inside to mark time segments. 132 00:07:10,600 --> 00:07:13,760 Speaker 1: And the object that was to cast a shadow would 133 00:07:13,800 --> 00:07:17,160 Speaker 1: be an appropriate distance from the sides of that bowl, 134 00:07:17,560 --> 00:07:21,480 Speaker 1: and it's orientation would be such that no matter which 135 00:07:21,480 --> 00:07:23,800 Speaker 1: way it's facing, it's facing away where the sun is 136 00:07:23,800 --> 00:07:26,520 Speaker 1: always going to cast a shadow against the bowl. So 137 00:07:26,600 --> 00:07:29,400 Speaker 1: you want to make sure that it's facing the right direction, 138 00:07:29,480 --> 00:07:31,800 Speaker 1: otherwise you get a part of the day where the 139 00:07:31,840 --> 00:07:34,600 Speaker 1: shadow would be outside the bowl and you would say 140 00:07:34,640 --> 00:07:38,040 Speaker 1: it is the end of times and cause a panic. Now. 141 00:07:38,080 --> 00:07:41,960 Speaker 1: I learned more about Sundale construction by visiting a website 142 00:07:41,960 --> 00:07:45,480 Speaker 1: called sun dials dot org. It's a site dedicated to 143 00:07:45,520 --> 00:07:48,480 Speaker 1: the art and science of sun dials, which is pretty 144 00:07:48,520 --> 00:07:52,679 Speaker 1: fascinating stuff, even to a liberal arts major such as myself. 145 00:07:52,680 --> 00:07:54,960 Speaker 1: For one thing, I learned that the two parts of 146 00:07:54,960 --> 00:07:57,480 Speaker 1: your basic sun dial, like the kind you might see 147 00:07:57,520 --> 00:08:00,400 Speaker 1: in a park or a garden, are the dial plate 148 00:08:00,880 --> 00:08:04,440 Speaker 1: and the nomon g n O m o n The 149 00:08:04,520 --> 00:08:07,600 Speaker 1: gnomon is the thing that casts a shadow onto the 150 00:08:07,640 --> 00:08:10,160 Speaker 1: dial plate. And you've probably seen sun dials that have 151 00:08:10,160 --> 00:08:13,920 Speaker 1: a common nomon that has set an angle respective to 152 00:08:14,080 --> 00:08:16,440 Speaker 1: the dial plate, so it comes up almost like a 153 00:08:16,520 --> 00:08:20,440 Speaker 1: triangle sticking up out of this circular dial. I learned 154 00:08:20,440 --> 00:08:23,920 Speaker 1: from sundals dot org that that angle should equal the 155 00:08:24,000 --> 00:08:28,120 Speaker 1: location's latitude. The markings on the dial plate also depend 156 00:08:28,240 --> 00:08:31,520 Speaker 1: upon the latitude of the location. Only by pairing these 157 00:08:31,560 --> 00:08:33,599 Speaker 1: two will you get a reliable way to mark the 158 00:08:33,640 --> 00:08:36,640 Speaker 1: passage of time throughout the year at that location, and 159 00:08:36,720 --> 00:08:40,800 Speaker 1: of course only on sunny days. Sun dials would continue 160 00:08:40,840 --> 00:08:44,760 Speaker 1: to be an important method of timekeeping for thousands of years. 161 00:08:44,760 --> 00:08:48,120 Speaker 1: It was only with the development and refinement of mechanical 162 00:08:48,200 --> 00:08:50,840 Speaker 1: clocks that sun dials even fell out of use in 163 00:08:50,920 --> 00:08:54,120 Speaker 1: naval ships in the seventeen hundreds. But sun dials were 164 00:08:54,160 --> 00:08:57,040 Speaker 1: just one method of keeping time in those early days. 165 00:08:57,360 --> 00:09:00,800 Speaker 1: Another method was to use a water clock. Now, a 166 00:09:00,840 --> 00:09:03,720 Speaker 1: basic water clock is sort of like an hour glass, 167 00:09:03,880 --> 00:09:06,280 Speaker 1: which of course is another form of ancient timekeeping, but 168 00:09:06,360 --> 00:09:10,120 Speaker 1: we'll set that aside. So you have two containers, typically 169 00:09:10,200 --> 00:09:13,360 Speaker 1: in a very simple water clock, connected by a tube 170 00:09:13,480 --> 00:09:16,400 Speaker 1: or a channel of some sort. One container is set 171 00:09:16,520 --> 00:09:18,920 Speaker 1: higher than the other, and it has water in it, 172 00:09:19,040 --> 00:09:23,280 Speaker 1: and gravity pulls that water, so it flows down into 173 00:09:23,520 --> 00:09:27,000 Speaker 1: the lower container through the tube or the channel in 174 00:09:27,040 --> 00:09:30,199 Speaker 1: a more or less controlled way. The lower container has 175 00:09:30,240 --> 00:09:33,080 Speaker 1: markings on the inside of it indicating how much time 176 00:09:33,080 --> 00:09:35,360 Speaker 1: has passed based upon the amount of water in the 177 00:09:35,400 --> 00:09:38,960 Speaker 1: second container. Occasionally you have to dump out the water 178 00:09:39,080 --> 00:09:41,480 Speaker 1: in the lower container and refill the water in the 179 00:09:41,559 --> 00:09:45,319 Speaker 1: upper container. Otherwise the clock just runs out of water. 180 00:09:45,559 --> 00:09:47,120 Speaker 1: You can't tell the time anymore. It's kind of like 181 00:09:47,160 --> 00:09:50,280 Speaker 1: if a a watch that has a spring in it, 182 00:09:50,440 --> 00:09:53,280 Speaker 1: once it unwinds all the way, it won't keep time anymore. 183 00:09:53,320 --> 00:09:56,319 Speaker 1: Same sort of thing here. Now. The method had one 184 00:09:56,400 --> 00:09:59,800 Speaker 1: major advantage over sun dials, because it would work what 185 00:10:00,000 --> 00:10:02,680 Speaker 1: there the sun was out or not. But it wasn't 186 00:10:02,720 --> 00:10:07,400 Speaker 1: necessarily always consistent. Even a well designed water clock couldn't 187 00:10:07,440 --> 00:10:10,920 Speaker 1: regulate the flow of water precisely enough to keep excellent time. 188 00:10:11,240 --> 00:10:14,400 Speaker 1: But it worked well enough for most folks. It wasn't 189 00:10:14,480 --> 00:10:17,240 Speaker 1: like you had a whole bunch of people saying, uh, 190 00:10:17,280 --> 00:10:19,680 Speaker 1: you know, over here in the fiefdom, I've gotta go 191 00:10:19,760 --> 00:10:24,280 Speaker 1: meet my lord for talking about how much corn. I've 192 00:10:25,040 --> 00:10:28,280 Speaker 1: harvested um, and I've got a three fifteen meeting, so 193 00:10:28,360 --> 00:10:30,640 Speaker 1: i really need this water clock to be precise. Now, 194 00:10:30,679 --> 00:10:33,680 Speaker 1: that just didn't happen in those days. Now, water clocks 195 00:10:33,800 --> 00:10:36,800 Speaker 1: date as far back as fifteen hundred b c. E. 196 00:10:37,120 --> 00:10:41,200 Speaker 1: The Greeks would call their water clocks clipsid draws. Now 197 00:10:41,440 --> 00:10:44,959 Speaker 1: that actually means water thieves, as the word comes from 198 00:10:45,080 --> 00:10:48,280 Speaker 1: clip time, meaning to steal. You might have heard the 199 00:10:48,400 --> 00:10:52,480 Speaker 1: term kleptomaniac that's someone who has a compulsion to steal things, 200 00:10:52,559 --> 00:10:56,680 Speaker 1: and high door, which means water. They started using water 201 00:10:56,720 --> 00:11:00,560 Speaker 1: clocks around three b C. And then since than everyone 202 00:11:00,640 --> 00:11:04,160 Speaker 1: uses clepsydras to be the term for water clocks. And 203 00:11:04,200 --> 00:11:07,839 Speaker 1: there are several variations. I described the simple one just 204 00:11:07,880 --> 00:11:10,560 Speaker 1: a second ago, but others might involve one vessel dipping 205 00:11:10,559 --> 00:11:13,640 Speaker 1: water out of a small hole into a second vessel 206 00:11:13,720 --> 00:11:17,120 Speaker 1: which has markings on this inside identicate the passing of time. 207 00:11:17,200 --> 00:11:19,200 Speaker 1: Or you could have a single vessel with markings on 208 00:11:19,200 --> 00:11:22,080 Speaker 1: the inside that are revealed as the water level decreases 209 00:11:22,400 --> 00:11:24,360 Speaker 1: when water drips out of it. So, in other words, 210 00:11:24,400 --> 00:11:28,200 Speaker 1: you create a small hole in a vessel, you fill 211 00:11:28,280 --> 00:11:31,520 Speaker 1: the vessel with water, and it's sort of a reverse 212 00:11:31,559 --> 00:11:35,120 Speaker 1: of what I was talking about. Before the more water 213 00:11:35,760 --> 00:11:39,959 Speaker 1: leaks out of the container, you see more markers telling 214 00:11:40,000 --> 00:11:43,920 Speaker 1: you what hour it is. In North Africa, people would 215 00:11:43,960 --> 00:11:46,960 Speaker 1: mark time by placing a metal bowl with a hole 216 00:11:47,120 --> 00:11:50,920 Speaker 1: in it inside a larger container of water, and they 217 00:11:50,920 --> 00:11:53,880 Speaker 1: marked the passing of time by the sinking of that 218 00:11:53,920 --> 00:11:56,760 Speaker 1: metal bowl. It would sink within a certain amount of time, 219 00:11:56,760 --> 00:11:58,600 Speaker 1: and that method was used in some parts of Africa 220 00:11:58,640 --> 00:12:02,120 Speaker 1: as late as the twentieth cent well. Many water clocks 221 00:12:02,120 --> 00:12:07,000 Speaker 1: were simple, some were devilishly complicated. For example, the water 222 00:12:07,120 --> 00:12:10,960 Speaker 1: clock tower built by Sue Song in the eleventh century CE. 223 00:12:11,200 --> 00:12:14,880 Speaker 1: Historians descriptions of Sue Song put him in that rare 224 00:12:15,080 --> 00:12:18,480 Speaker 1: category of humans that includes other amazing polly maths like 225 00:12:18,600 --> 00:12:22,400 Speaker 1: Leonardo da Vinci. He was a cartographer, he was a mathematician, 226 00:12:22,520 --> 00:12:25,160 Speaker 1: he was a physician, and he was a horologist. Now 227 00:12:25,200 --> 00:12:28,400 Speaker 1: that last one essentially means he was a clockmaker. Sue 228 00:12:28,440 --> 00:12:31,160 Speaker 1: Song and a team of mathematicians came up with the 229 00:12:31,240 --> 00:12:34,960 Speaker 1: idea for the mechanics that would make the clock tower possible. 230 00:12:35,360 --> 00:12:39,840 Speaker 1: The tower was pretty tall, uh. It had inside of 231 00:12:39,880 --> 00:12:43,040 Speaker 1: it several levels, like it was three stories tall. The 232 00:12:43,120 --> 00:12:46,760 Speaker 1: top level had a model of the universe on it. 233 00:12:46,880 --> 00:12:49,960 Speaker 1: The middle one had kind of a a globe to 234 00:12:50,000 --> 00:12:53,360 Speaker 1: show you what constellations would be where at what point 235 00:12:53,480 --> 00:12:56,600 Speaker 1: point of the year, so sort of an astronomical slash 236 00:12:56,640 --> 00:13:01,160 Speaker 1: astrological clock. And then the base level had the actual 237 00:13:01,320 --> 00:13:06,040 Speaker 1: time piece itself. Uh. There was a vertically aligned water 238 00:13:06,120 --> 00:13:10,000 Speaker 1: wheel which was eleven feet in diameter, So think of 239 00:13:10,000 --> 00:13:13,720 Speaker 1: a wheel on its side. It's it's you know, vertically aligned, 240 00:13:13,720 --> 00:13:17,760 Speaker 1: it's got scoops on the outer edge of it. Water 241 00:13:17,800 --> 00:13:20,960 Speaker 1: would flow from a giant container through a narrow slit 242 00:13:21,000 --> 00:13:24,240 Speaker 1: at the container's base, and that water would then fill 243 00:13:24,480 --> 00:13:27,920 Speaker 1: whichever of the thirty six scoops mounted on the outside 244 00:13:27,920 --> 00:13:32,040 Speaker 1: of the wheel was level with that that drainage spot. 245 00:13:32,960 --> 00:13:35,600 Speaker 1: So water flows out of the container and it starts 246 00:13:35,640 --> 00:13:39,040 Speaker 1: to fill up that that scoop. Once the scoop got 247 00:13:39,080 --> 00:13:42,520 Speaker 1: heavy enough, the wheel would rotate, which in turn would 248 00:13:42,520 --> 00:13:45,280 Speaker 1: power all the other gears in the tower and help 249 00:13:45,360 --> 00:13:49,720 Speaker 1: keep time. Now, a series of horizontally aligned gears on 250 00:13:50,040 --> 00:13:53,559 Speaker 1: this tower had small figurines mounted to the outer edges. 251 00:13:53,600 --> 00:13:57,320 Speaker 1: So these gears are are all horizontal, not vertical, so 252 00:13:57,320 --> 00:14:00,960 Speaker 1: they're at a nine degree angle relative to the water wheel. 253 00:14:01,480 --> 00:14:03,640 Speaker 1: The figurines were positioned in such a way to be 254 00:14:03,679 --> 00:14:06,800 Speaker 1: easily seen through windows of the tower, So if you 255 00:14:06,840 --> 00:14:09,280 Speaker 1: looked at the tower from the outside, you'd see these 256 00:14:09,320 --> 00:14:13,040 Speaker 1: little figures in various windows along that side, like three 257 00:14:13,120 --> 00:14:18,520 Speaker 1: levels of them, with one window showing certain figures that 258 00:14:18,640 --> 00:14:21,800 Speaker 1: indicate a certain increment of time. The figures all carried 259 00:14:21,880 --> 00:14:26,080 Speaker 1: signs that represent numbers. That means they were effectively digit counters, 260 00:14:26,880 --> 00:14:29,000 Speaker 1: so you look at the figures and you could suss 261 00:14:29,040 --> 00:14:31,520 Speaker 1: out what time it is. But Sue Song had to 262 00:14:31,560 --> 00:14:33,920 Speaker 1: come up with a way to make this a steady, 263 00:14:34,240 --> 00:14:37,680 Speaker 1: regular series of events. If you left this on its own, 264 00:14:37,720 --> 00:14:40,560 Speaker 1: if you just had a big water wheel and you 265 00:14:40,600 --> 00:14:43,400 Speaker 1: were having water flow into these scoops, the water wheel 266 00:14:43,400 --> 00:14:46,400 Speaker 1: would eventually just start turning continuously as long as there 267 00:14:46,480 --> 00:14:49,200 Speaker 1: was water to push it, which means all the figures 268 00:14:49,200 --> 00:14:51,720 Speaker 1: would constantly be in motion, and that could be tricky 269 00:14:51,760 --> 00:14:55,080 Speaker 1: to read the time, especially between minutes. So you know, 270 00:14:55,200 --> 00:14:56,960 Speaker 1: you could have a figure that's half in view and 271 00:14:57,000 --> 00:14:59,120 Speaker 1: half out of you you're not really sure what time 272 00:14:59,120 --> 00:15:01,280 Speaker 1: it is. So Song need a way to keep a 273 00:15:01,320 --> 00:15:05,680 Speaker 1: gear in position for a certain interval a given amount 274 00:15:05,720 --> 00:15:08,440 Speaker 1: of time, such as a minute, and so he and 275 00:15:08,480 --> 00:15:10,240 Speaker 1: his team had to come up with a way of 276 00:15:10,280 --> 00:15:13,400 Speaker 1: stopping gears, but only temporarily, so that the passage of 277 00:15:13,400 --> 00:15:16,800 Speaker 1: time could be more regularly communicated. So he and his 278 00:15:16,880 --> 00:15:19,280 Speaker 1: team created a clever gadget that would end up being 279 00:15:19,280 --> 00:15:24,480 Speaker 1: an important part of clocks for centuries. It's called an escapement. 280 00:15:25,200 --> 00:15:28,440 Speaker 1: So what is an escapement. We'll go into that in 281 00:15:28,520 --> 00:15:31,600 Speaker 1: just a bit, but first let's take a quick break 282 00:15:31,840 --> 00:15:43,360 Speaker 1: to thank our sponsor. Okay, So, an escapement, what isn't 283 00:15:43,840 --> 00:15:46,760 Speaker 1: well in clocks is an element within a device that 284 00:15:46,920 --> 00:15:50,120 Speaker 1: regulates the turning of other gears. You can think of 285 00:15:50,120 --> 00:15:53,760 Speaker 1: it as a lock that unlocks itself at consistent intervals 286 00:15:53,760 --> 00:15:56,640 Speaker 1: to allow gears to turn before locking back in place. 287 00:15:57,080 --> 00:16:00,240 Speaker 1: And if you've ever seen a pendulum clock, that the 288 00:16:00,360 --> 00:16:03,000 Speaker 1: purpose for that pendulum. But we'll get into that a 289 00:16:03,000 --> 00:16:06,360 Speaker 1: little bit later. Sue Song created an escapement to lock 290 00:16:06,520 --> 00:16:09,040 Speaker 1: the gears in place in his water tower until there 291 00:16:09,080 --> 00:16:10,840 Speaker 1: was a need for them to shift to the next 292 00:16:10,920 --> 00:16:14,400 Speaker 1: increment of time. Sue Song's approach was using a balance 293 00:16:14,480 --> 00:16:18,360 Speaker 1: called a steel yard. It's all one word. Steel yards 294 00:16:18,400 --> 00:16:21,320 Speaker 1: are pretty cool applications of one of the simplest machines 295 00:16:21,480 --> 00:16:24,120 Speaker 1: the lever. If you have a lever with a pivot 296 00:16:24,160 --> 00:16:27,440 Speaker 1: point in the exact center of its length, assuming the 297 00:16:27,480 --> 00:16:30,680 Speaker 1: mass is equal on both sides, the lever will balance 298 00:16:30,720 --> 00:16:34,160 Speaker 1: out if you put two equal weights, two equal masses 299 00:16:34,200 --> 00:16:37,840 Speaker 1: really on either end, and it remains balanced. Well. It 300 00:16:37,920 --> 00:16:40,320 Speaker 1: does so because of this very nature of levers. So 301 00:16:40,440 --> 00:16:42,760 Speaker 1: are you with me so far? Now imagine that we 302 00:16:42,800 --> 00:16:45,960 Speaker 1: move that pivot point more toward the right side of 303 00:16:46,000 --> 00:16:48,560 Speaker 1: the lever. That would mean that more of the lever's 304 00:16:48,640 --> 00:16:51,680 Speaker 1: mass is on the left side. The right side is 305 00:16:51,720 --> 00:16:53,840 Speaker 1: shorter than the left side because we've moved the pivot 306 00:16:53,880 --> 00:16:56,400 Speaker 1: point closer to the right end. So if you just 307 00:16:56,440 --> 00:16:58,360 Speaker 1: step back the left side, the lever will be on 308 00:16:58,400 --> 00:17:00,720 Speaker 1: the ground. It's gonna tilt downward it until it's either 309 00:17:00,800 --> 00:17:02,960 Speaker 1: on the ground, or if you haven't suspended in the air, 310 00:17:03,360 --> 00:17:07,640 Speaker 1: it's gonna be dangling vertically with the short end at 311 00:17:07,640 --> 00:17:10,199 Speaker 1: the top, you know, the bit that's closer to the pivot. 312 00:17:10,720 --> 00:17:13,800 Speaker 1: So to balance it out, you would have to put 313 00:17:13,840 --> 00:17:16,200 Speaker 1: more weight on the right side. You would have to 314 00:17:16,240 --> 00:17:19,479 Speaker 1: have more mass to equal out the mass that's on 315 00:17:19,520 --> 00:17:21,920 Speaker 1: the left and balance it all out. This is how 316 00:17:21,920 --> 00:17:24,720 Speaker 1: a steel yard works, and you may have used one 317 00:17:24,720 --> 00:17:27,399 Speaker 1: of these with weight scales. If you've ever stepped on 318 00:17:27,440 --> 00:17:30,199 Speaker 1: a scale that requires you to move a counterweight along 319 00:17:30,200 --> 00:17:33,080 Speaker 1: an arm, you've used a steel yard. The trick is 320 00:17:33,080 --> 00:17:35,919 Speaker 1: to get the counterweight adjust the right spot on the 321 00:17:36,000 --> 00:17:39,040 Speaker 1: lever to make the arm balance out. If the counterweight 322 00:17:39,119 --> 00:17:41,320 Speaker 1: is too close to the pivot point, the arm will 323 00:17:41,520 --> 00:17:43,240 Speaker 1: be up in the air. It will say no, you 324 00:17:43,359 --> 00:17:46,720 Speaker 1: weigh more than that. You need to push that counterweight 325 00:17:46,760 --> 00:17:49,440 Speaker 1: further towards the end of the arm. If it's too 326 00:17:49,480 --> 00:17:51,600 Speaker 1: close to the end of the arm, it's gonna go 327 00:17:51,720 --> 00:17:53,800 Speaker 1: down as far as it can go. Like in a scale, 328 00:17:53,800 --> 00:17:56,840 Speaker 1: there's typically a little stop point and it'll just sink 329 00:17:56,880 --> 00:17:58,760 Speaker 1: to the bottom. So getting the counterweight in the right 330 00:17:58,800 --> 00:18:01,000 Speaker 1: position makes the arm ba elens in the middle, and 331 00:18:01,040 --> 00:18:03,600 Speaker 1: the position of the counterweight will tell you how much 332 00:18:03,760 --> 00:18:07,040 Speaker 1: you way. There will be some marking. They're saying, congratulations, 333 00:18:07,080 --> 00:18:10,240 Speaker 1: away a hundred fifty pounds. Sue Song's tower used a 334 00:18:10,280 --> 00:18:12,359 Speaker 1: steel lyard kind of like this. Now, I want you 335 00:18:12,400 --> 00:18:15,680 Speaker 1: to imagine a vertical wheel made of spoons. All right, 336 00:18:16,040 --> 00:18:18,920 Speaker 1: All the spoons are facing in the same direction, and 337 00:18:19,040 --> 00:18:21,840 Speaker 1: all the scoop parts of the spoon are faced in 338 00:18:21,880 --> 00:18:25,560 Speaker 1: such a way where they're you know, they're just if 339 00:18:25,600 --> 00:18:26,960 Speaker 1: you were to stack them in a stack, they would 340 00:18:27,000 --> 00:18:29,720 Speaker 1: all be stacked together perfectly, but you've fanned them out 341 00:18:29,760 --> 00:18:34,160 Speaker 1: into this circle. It's a vertical circle. Uh. And imagine 342 00:18:34,160 --> 00:18:36,280 Speaker 1: we're looking at this wheel from the side, so we're 343 00:18:36,280 --> 00:18:39,640 Speaker 1: looking at the profile of the wheel, not dead on position. 344 00:18:39,680 --> 00:18:42,320 Speaker 1: Halfway up the wheel to one side is a chamber 345 00:18:42,359 --> 00:18:45,959 Speaker 1: of water that can flow out into the empty spoon 346 00:18:46,520 --> 00:18:49,520 Speaker 1: that is next to it. The one that's closest to it. 347 00:18:49,560 --> 00:18:52,639 Speaker 1: Will say that this this spoon is parallel to the ground, 348 00:18:53,119 --> 00:18:56,000 Speaker 1: So this is the one that is at the three 349 00:18:56,040 --> 00:18:59,200 Speaker 1: o'clock position for those of you who still know how 350 00:18:59,280 --> 00:19:02,240 Speaker 1: to read analog clocks. On the other side of the wheel, 351 00:19:02,280 --> 00:19:05,440 Speaker 1: over at the nine o'clock position is a weighted arm, 352 00:19:05,800 --> 00:19:09,040 Speaker 1: and it rests on the back of the spoon opposite 353 00:19:09,080 --> 00:19:12,360 Speaker 1: to the one getting filled. And the weighted arm, it 354 00:19:12,400 --> 00:19:16,919 Speaker 1: can't reverse the direction of the wheel. It just holds 355 00:19:16,960 --> 00:19:19,480 Speaker 1: it in place. The weight of that arm just keeps 356 00:19:19,520 --> 00:19:22,439 Speaker 1: it locked there. But the weighted arm is on a pivot, 357 00:19:22,800 --> 00:19:26,560 Speaker 1: so it can be lifted if enough force is applied. Now, 358 00:19:26,600 --> 00:19:29,920 Speaker 1: as soon as the spoon fills with water, it gets heavier. 359 00:19:30,680 --> 00:19:32,800 Speaker 1: When it gets heavy enough to counteract the weighted arm 360 00:19:32,800 --> 00:19:35,879 Speaker 1: on the other side, the weighted arm pivots up. This 361 00:19:35,960 --> 00:19:40,000 Speaker 1: allows the wheel of spoons to turn in one increment. 362 00:19:40,520 --> 00:19:43,320 Speaker 1: It turns so that the next spoon is moved into place. 363 00:19:43,520 --> 00:19:46,359 Speaker 1: The weighted arms slips off the back of the spoon 364 00:19:46,480 --> 00:19:48,720 Speaker 1: it had been on and comes down to prevent the 365 00:19:48,760 --> 00:19:51,960 Speaker 1: next one from moving upward, locks it into place. That 366 00:19:52,040 --> 00:19:55,720 Speaker 1: whole process repeats, and that's basically how siouxs Song's escapement worked. 367 00:19:55,760 --> 00:19:59,000 Speaker 1: As long as there was water steadily flowing into the tower, 368 00:19:59,440 --> 00:20:03,080 Speaker 1: the clock would keep accurate time. Now I wish I 369 00:20:03,119 --> 00:20:05,479 Speaker 1: could tell you that you could go and visit this 370 00:20:05,560 --> 00:20:09,879 Speaker 1: amazing clock tower in Kaifeng, but sadly you can't. The 371 00:20:09,960 --> 00:20:13,240 Speaker 1: tower was finished in ten ninety four. Sue Song himself 372 00:20:13,280 --> 00:20:16,360 Speaker 1: died in eleven oh one, which means he didn't live 373 00:20:16,400 --> 00:20:20,040 Speaker 1: to see his amazing creation disassembled by soldiers. After the 374 00:20:20,040 --> 00:20:24,680 Speaker 1: Manchurian Army invaded Kaifeng, they took the clocks pieces back 375 00:20:24,720 --> 00:20:28,880 Speaker 1: to their capital, which is today's modern Beijing. They attempted 376 00:20:28,920 --> 00:20:31,879 Speaker 1: to reassemble it, but the complex nature of the clock 377 00:20:32,000 --> 00:20:35,920 Speaker 1: confounded them and it never worked again. There is, however, 378 00:20:36,440 --> 00:20:40,480 Speaker 1: a working replica of the tower in the Gishido Suwako 379 00:20:40,800 --> 00:20:44,240 Speaker 1: Watch and Clock Museum in the Nagano Prefecture in Japan. 380 00:20:44,960 --> 00:20:47,520 Speaker 1: I've seen photos of it and it is gorgeous. I 381 00:20:47,560 --> 00:20:50,600 Speaker 1: hope one day to see it in person. This particular 382 00:20:50,800 --> 00:20:54,639 Speaker 1: replica was built based upon the best understanding of sus 383 00:20:54,640 --> 00:20:58,760 Speaker 1: Song's designs. Many of those designs survived all of that 384 00:20:59,520 --> 00:21:04,200 Speaker 1: invade Jian issue, but there were little details left out, 385 00:21:04,280 --> 00:21:08,159 Speaker 1: so people the modern replica makers had to kind of 386 00:21:08,160 --> 00:21:10,680 Speaker 1: fudge things here and there to make it work properly. 387 00:21:10,760 --> 00:21:14,560 Speaker 1: So it may not be one to one a replica, 388 00:21:14,720 --> 00:21:17,439 Speaker 1: but it's really close and it looks amazing in the 389 00:21:17,440 --> 00:21:20,320 Speaker 1: pictures I've seen. This escapement would prove to be a 390 00:21:20,440 --> 00:21:23,160 Speaker 1: very important component of clocks and watches as the art 391 00:21:23,160 --> 00:21:27,080 Speaker 1: and science of clockmaking evolved. As for purely mechanical clocks 392 00:21:27,119 --> 00:21:30,800 Speaker 1: that did not depend upon water, their origin is somewhat 393 00:21:30,840 --> 00:21:35,000 Speaker 1: lost to time, which is not an irony but seems fitting. 394 00:21:35,320 --> 00:21:40,159 Speaker 1: Monasteries were building clock towers called turret clocks as early 395 00:21:40,359 --> 00:21:43,600 Speaker 1: as the fourteenth century, at least maybe earlier. These were 396 00:21:43,720 --> 00:21:47,080 Speaker 1: massive towers that passed marked the passing of time by 397 00:21:47,119 --> 00:21:50,480 Speaker 1: tolling a bell, so there were no dials or hands 398 00:21:50,560 --> 00:21:53,080 Speaker 1: or other indications of what time it is. The machinery 399 00:21:53,200 --> 00:21:57,040 Speaker 1: was large and relied upon weights and gears. Now, the 400 00:21:57,040 --> 00:21:59,919 Speaker 1: weight is a very important part of these early make 401 00:22:00,040 --> 00:22:03,399 Speaker 1: chanical clocks. And here's how a weighted clock works. Now, 402 00:22:03,480 --> 00:22:07,639 Speaker 1: imagine you have an axle wound around That axle is 403 00:22:07,800 --> 00:22:10,239 Speaker 1: a cable or rope. If you were to pull on 404 00:22:10,359 --> 00:22:14,040 Speaker 1: that cable or rope, it would provide enough rotational force 405 00:22:14,119 --> 00:22:17,320 Speaker 1: to make the axle rotate. At the end of this 406 00:22:17,400 --> 00:22:20,159 Speaker 1: rope is a heavy weight, and if you lock the 407 00:22:20,160 --> 00:22:23,200 Speaker 1: axle into place, the weight represents potential energy. Right it's 408 00:22:23,600 --> 00:22:27,080 Speaker 1: hanging it suspended above the ground, but the wheel is 409 00:22:27,119 --> 00:22:30,160 Speaker 1: locked so it cannot turn. That's potential energy. The weight 410 00:22:30,240 --> 00:22:33,000 Speaker 1: has the potential to move the clock or move this 411 00:22:33,080 --> 00:22:36,720 Speaker 1: wheel this axle. Gravity is pulling the weight down towards 412 00:22:36,760 --> 00:22:39,439 Speaker 1: the center of the earth, and once you unlock the wheel, 413 00:22:39,720 --> 00:22:42,919 Speaker 1: it allows that potential energy to convert into kinetic energy. 414 00:22:42,960 --> 00:22:45,760 Speaker 1: The weight will start to drop toward the ground and 415 00:22:45,920 --> 00:22:49,360 Speaker 1: it applies for uce to the rope, which thus applies 416 00:22:49,400 --> 00:22:52,080 Speaker 1: force to the axle, causing it to rotate. And then 417 00:22:52,119 --> 00:22:54,280 Speaker 1: it can end up making other elements of the clock 418 00:22:54,680 --> 00:22:57,520 Speaker 1: move as well. You have gears and pinions and stuff, 419 00:22:57,560 --> 00:23:00,199 Speaker 1: and they're all interlocked, and that allows for or the 420 00:23:00,200 --> 00:23:03,000 Speaker 1: operation of a clock, which ultimately makes a bell go 421 00:23:03,200 --> 00:23:09,080 Speaker 1: ding dong ding. But here's a problem. Gravity causes acceleration. 422 00:23:09,640 --> 00:23:14,040 Speaker 1: Things do not fall at a steady velocity. The velocity 423 00:23:14,119 --> 00:23:16,960 Speaker 1: is always increasing as long as the fall is continuing, 424 00:23:17,040 --> 00:23:20,879 Speaker 1: at least until you hit terminal velocity. So everything accelerates 425 00:23:20,880 --> 00:23:23,800 Speaker 1: according to the gravitational pull of the Earth. At least 426 00:23:23,920 --> 00:23:26,679 Speaker 1: stuff dropped here on Earth does that. If you were 427 00:23:26,720 --> 00:23:29,280 Speaker 1: to drop something on Mars, it would accelerate according to 428 00:23:29,320 --> 00:23:32,880 Speaker 1: Mars's gravity, not Earth's gravity, even if it originally came 429 00:23:32,880 --> 00:23:36,480 Speaker 1: from Earth, because Mars just don't care. But here on 430 00:23:36,560 --> 00:23:39,760 Speaker 1: Earth we know gravitational acceleration is equal to nine point 431 00:23:39,800 --> 00:23:43,680 Speaker 1: eight meters per second per second. So if you drop 432 00:23:43,680 --> 00:23:46,320 Speaker 1: a weight high enough for it to fall for several seconds, 433 00:23:46,720 --> 00:23:48,879 Speaker 1: each second that passes will see the velocity of the 434 00:23:48,920 --> 00:23:52,720 Speaker 1: falling object increase by nine point eight meters. So after 435 00:23:52,800 --> 00:23:55,080 Speaker 1: one second, the weight is falling at nine point eight 436 00:23:55,200 --> 00:23:58,720 Speaker 1: ms per second downwards. During second number two, the weight 437 00:23:58,840 --> 00:24:02,320 Speaker 1: is falling at nineteen point six meters per second downwards, 438 00:24:02,560 --> 00:24:05,720 Speaker 1: and so on. It increases each second the weights falling 439 00:24:05,800 --> 00:24:09,919 Speaker 1: speed increases until the weight achieves terminal velocity. I mentioned 440 00:24:09,920 --> 00:24:12,840 Speaker 1: that earlier. This is the speed and object reaches when 441 00:24:12,840 --> 00:24:16,480 Speaker 1: the resistance of the medium it is falling through. In 442 00:24:16,520 --> 00:24:18,600 Speaker 1: our examples, we're just talking about Earth, so we're talking 443 00:24:18,640 --> 00:24:22,439 Speaker 1: about Earth's atmosphere. When the resistance of Earth's atmosphere is 444 00:24:22,560 --> 00:24:26,240 Speaker 1: enough to prevent it from accelerating further, then the object 445 00:24:26,320 --> 00:24:30,640 Speaker 1: has reached terminal velocity. So eventually, falling speed does top out, 446 00:24:30,760 --> 00:24:34,280 Speaker 1: and it remains consistent at that point until you know, 447 00:24:35,160 --> 00:24:37,720 Speaker 1: you collide with the ground, in which case the falling 448 00:24:37,720 --> 00:24:41,399 Speaker 1: speed stops and the splatting speed begins. Okay, but what 449 00:24:41,480 --> 00:24:43,919 Speaker 1: does that have to do with clocks. Well, remember at 450 00:24:43,920 --> 00:24:45,480 Speaker 1: the top of the show I said that a clock 451 00:24:45,560 --> 00:24:49,480 Speaker 1: needs some sort of consistent, regular action or process that 452 00:24:49,560 --> 00:24:52,480 Speaker 1: gives you the ability to mark off equal increments of time. 453 00:24:53,040 --> 00:24:56,639 Speaker 1: If you have an accelerating falling weight, it's tricky to 454 00:24:56,760 --> 00:24:59,240 Speaker 1: use it as a means for the rest of your structure, 455 00:24:59,480 --> 00:25:02,280 Speaker 1: right because it would have to account for that acceleration. 456 00:25:02,840 --> 00:25:06,120 Speaker 1: You would have to have some really complex machinery that 457 00:25:06,280 --> 00:25:10,480 Speaker 1: would operate in such a way to counteract that acceleration. 458 00:25:10,640 --> 00:25:14,120 Speaker 1: You'd much rather have a regular force that remains consistent 459 00:25:14,400 --> 00:25:17,960 Speaker 1: in speed and power, something that's not going to increase 460 00:25:18,000 --> 00:25:21,240 Speaker 1: an amplitude over time. And that's where the design of 461 00:25:21,280 --> 00:25:25,000 Speaker 1: an escapement is so important. The escapement design allows clockmakers 462 00:25:25,000 --> 00:25:27,639 Speaker 1: to regulate this action and make sure it happens at 463 00:25:27,680 --> 00:25:32,080 Speaker 1: these regular intervals. Now, the oldest surviving mechanical clock in 464 00:25:32,119 --> 00:25:36,680 Speaker 1: England is Salisbury Cathedral's clock. The clock dates to probably 465 00:25:36,720 --> 00:25:40,600 Speaker 1: around thirteen eighty six. According to historians, this is not 466 00:25:40,680 --> 00:25:44,720 Speaker 1: necessarily the oldest surviving mechanical clock in the world. There's 467 00:25:44,720 --> 00:25:49,159 Speaker 1: actually some controversy about that, but this is certainly the 468 00:25:49,200 --> 00:25:52,280 Speaker 1: oldest surviving one in England. And I saw that clock 469 00:25:52,320 --> 00:25:55,359 Speaker 1: in person back in nine. I even had a photo 470 00:25:55,400 --> 00:25:57,800 Speaker 1: taken of me appearing to set my watch according to 471 00:25:57,840 --> 00:26:00,199 Speaker 1: the clock, which at the time I consider it to 472 00:26:00,240 --> 00:26:03,639 Speaker 1: be high comedy. And let's be honest, I'd probably do 473 00:26:03,720 --> 00:26:05,560 Speaker 1: the exact same thing today if I were to visit. 474 00:26:05,800 --> 00:26:09,479 Speaker 1: The Salisbury Cathedral clock originally had was called a verge 475 00:26:09,680 --> 00:26:13,240 Speaker 1: and folio escapement. Now, this is a tricky thing to 476 00:26:13,320 --> 00:26:16,680 Speaker 1: describe in an audio podcast, but I'm gonna try and 477 00:26:16,720 --> 00:26:20,719 Speaker 1: do my best. Imagine that you have a vertically aligned wheel, 478 00:26:21,080 --> 00:26:23,359 Speaker 1: kind of similar to the water wheel I was talking about, 479 00:26:23,840 --> 00:26:27,240 Speaker 1: but instead of the wheel's edge ending in scoops, the 480 00:26:27,280 --> 00:26:30,920 Speaker 1: wheel has pegs sticking out along the rim on one 481 00:26:31,040 --> 00:26:33,879 Speaker 1: side of it alright, So one side of the wheel 482 00:26:34,000 --> 00:26:38,040 Speaker 1: is is just flat, it's featureless. The other side of 483 00:26:38,040 --> 00:26:41,359 Speaker 1: the wheel has pegs sticking out right along the edge 484 00:26:41,400 --> 00:26:45,600 Speaker 1: at regular intervals. This is called the escape wheel. The 485 00:26:45,600 --> 00:26:48,600 Speaker 1: wheel is on an axle, and that axle at some 486 00:26:48,720 --> 00:26:51,600 Speaker 1: point has a weight attached to it. So left on 487 00:26:51,640 --> 00:26:54,280 Speaker 1: its own, the wheel would rotate as the weight falls, 488 00:26:54,680 --> 00:26:58,840 Speaker 1: with the rotation accelerating as the weight accelerated during its fall. 489 00:26:59,320 --> 00:27:01,560 Speaker 1: So we would have to have something to regulate the 490 00:27:01,560 --> 00:27:05,760 Speaker 1: wheel's rotation. The force applied to the axle should remain steady, 491 00:27:05,880 --> 00:27:08,640 Speaker 1: so we can't mess with the weight. We can't change that. 492 00:27:09,040 --> 00:27:12,680 Speaker 1: We need to have some other way to alter this, 493 00:27:13,280 --> 00:27:17,200 Speaker 1: and that would be the verge and folio. Position. Next 494 00:27:17,320 --> 00:27:20,280 Speaker 1: to this vertical wheel, the one that has the pegs 495 00:27:20,280 --> 00:27:24,040 Speaker 1: the escape wheel, you have a vertical rod. This rod 496 00:27:24,119 --> 00:27:27,560 Speaker 1: is called the verge. The verge can rotate on its 497 00:27:27,640 --> 00:27:33,320 Speaker 1: axis in either direction of rotation along its respective orientation. 498 00:27:33,760 --> 00:27:37,760 Speaker 1: The rod has two stoppers or protrusions that are called palettes. 499 00:27:38,440 --> 00:27:40,800 Speaker 1: They're like flaps like you know, they could just be 500 00:27:41,280 --> 00:27:45,160 Speaker 1: a little square flaps that stick out from the rod 501 00:27:45,280 --> 00:27:48,240 Speaker 1: to the side. One of those positioned near the top 502 00:27:48,240 --> 00:27:50,480 Speaker 1: of the vertical wheel, and one of them is positioned 503 00:27:50,480 --> 00:27:53,160 Speaker 1: towards the bottom of the vertical wheel, and their their 504 00:27:53,160 --> 00:27:58,280 Speaker 1: alignem is slightly offset in respect to the axis of 505 00:27:58,359 --> 00:28:01,760 Speaker 1: the verge. That means that they can catch the pegs 506 00:28:01,800 --> 00:28:05,439 Speaker 1: of the rotating vertical wheel at different points. So you 507 00:28:05,520 --> 00:28:08,840 Speaker 1: have these pegs that can come into contact with these palettes, 508 00:28:09,200 --> 00:28:12,920 Speaker 1: and when they do, obviously there's there's an impact there. 509 00:28:12,960 --> 00:28:16,400 Speaker 1: There's a collision, and it causes the verge to rotate 510 00:28:16,480 --> 00:28:19,280 Speaker 1: and it puts the other palette, the one on the 511 00:28:19,320 --> 00:28:22,119 Speaker 1: opposite side of the verge, into the right position to 512 00:28:22,200 --> 00:28:24,679 Speaker 1: catch the pegs on the opposite end of the wheel. 513 00:28:25,200 --> 00:28:30,040 Speaker 1: So one palette is always going to be pushed in 514 00:28:30,200 --> 00:28:33,440 Speaker 1: one direction of rotation for the verge, the other palette 515 00:28:33,480 --> 00:28:35,639 Speaker 1: is always going to be pushed in the other direction 516 00:28:35,680 --> 00:28:38,400 Speaker 1: of rotation for the verge. Because you have this ninety 517 00:28:38,480 --> 00:28:45,360 Speaker 1: degree difference of orientation with respect to the the escape wheel. 518 00:28:46,160 --> 00:28:50,960 Speaker 1: So the the the attached to the very top of 519 00:28:51,000 --> 00:28:55,120 Speaker 1: the verge is a horizontally balanced lever. It's actually kind 520 00:28:55,120 --> 00:28:58,440 Speaker 1: of kind of like another horizontal rod that's on the 521 00:28:58,520 --> 00:29:01,640 Speaker 1: very top of the verge. There's weights attached to either end. 522 00:29:01,680 --> 00:29:04,680 Speaker 1: This is called the folio, and it swings back and forth, 523 00:29:04,720 --> 00:29:07,560 Speaker 1: it oscillates. So how does it work? Well, As I said, 524 00:29:07,560 --> 00:29:09,680 Speaker 1: one palette is position so it catches pegs at the 525 00:29:09,680 --> 00:29:12,280 Speaker 1: top of the vertically aligned wheel, the escape wheel. The 526 00:29:12,320 --> 00:29:15,360 Speaker 1: other palettes at the bottom. They're offset, so one pallet 527 00:29:15,400 --> 00:29:17,320 Speaker 1: makes contact with the pegs, the other one is free 528 00:29:17,320 --> 00:29:20,000 Speaker 1: and clear. It doesn't interfere because otherwise, if you had 529 00:29:20,040 --> 00:29:23,520 Speaker 1: both palettes positioned so that they locked in with the pegs, 530 00:29:24,080 --> 00:29:26,560 Speaker 1: no movement could happen. You would effectively have a break 531 00:29:26,880 --> 00:29:30,280 Speaker 1: on that escape wheel and it would just not rotate. So, 532 00:29:30,560 --> 00:29:32,640 Speaker 1: as the vertical wheel turns, a peg at the top 533 00:29:32,640 --> 00:29:35,240 Speaker 1: of the wheel catches the top pallett and provides enough 534 00:29:35,280 --> 00:29:38,640 Speaker 1: force to push it and rotate the verge on its axis. 535 00:29:39,120 --> 00:29:42,200 Speaker 1: The folio at the top would rotate accordingly. Now, that 536 00:29:42,240 --> 00:29:44,480 Speaker 1: puts the palette at the lower end of the the 537 00:29:44,640 --> 00:29:47,560 Speaker 1: lever in position to catch a peg at the bottom 538 00:29:47,600 --> 00:29:50,320 Speaker 1: of the vertical wheel the escape wheel. Because of the 539 00:29:50,360 --> 00:29:53,960 Speaker 1: alignment of the virgin wheel, this creates a force opposing 540 00:29:53,960 --> 00:29:57,440 Speaker 1: the direction of the folio's previous rotation, making it rotate 541 00:29:57,440 --> 00:30:01,440 Speaker 1: the other way or oscillate. Uh. This is similar to 542 00:30:01,560 --> 00:30:04,920 Speaker 1: the oscillations of a pendulum, and we'll cover that when 543 00:30:04,920 --> 00:30:08,080 Speaker 1: we get to pendulum clocks. The pegs will catch the 544 00:30:08,120 --> 00:30:12,120 Speaker 1: pallets and create this TikTok sound you here with a clock. Uh. 545 00:30:12,120 --> 00:30:14,920 Speaker 1: It's the pegs making contact with those pallets and making 546 00:30:14,920 --> 00:30:17,440 Speaker 1: the folio swing one way or swing the other way. 547 00:30:17,720 --> 00:30:19,960 Speaker 1: The weights on the folio give it enough inertia to 548 00:30:20,080 --> 00:30:22,480 Speaker 1: keep it from rotating too far and provide just enough 549 00:30:22,520 --> 00:30:25,800 Speaker 1: force to regulate the turning of the vertical wheel. The 550 00:30:25,920 --> 00:30:28,600 Speaker 1: escape wheel is just one part of the clock. The 551 00:30:28,640 --> 00:30:31,120 Speaker 1: elements that actually track the time, as in the ones 552 00:30:31,160 --> 00:30:33,640 Speaker 1: that govern the movements of the hands on a dial 553 00:30:33,680 --> 00:30:38,600 Speaker 1: face or govern when a bell gets struck. That's called 554 00:30:38,640 --> 00:30:42,320 Speaker 1: the train or wheel work of a clock. These are 555 00:30:42,360 --> 00:30:44,480 Speaker 1: all the gears that transmit motion to the parts of 556 00:30:44,480 --> 00:30:47,200 Speaker 1: the clock that illustrate the time or market in some way. 557 00:30:47,520 --> 00:30:50,720 Speaker 1: In the earlier clocks, this was pretty primitive, as originally again, 558 00:30:50,720 --> 00:30:53,040 Speaker 1: there were no dials or hands to turn. There just 559 00:30:53,080 --> 00:30:56,120 Speaker 1: need to be a way to designate an hour had passed. Later, 560 00:30:56,160 --> 00:30:58,880 Speaker 1: clocks would add an hour hand, but no minute hand, 561 00:30:59,120 --> 00:31:00,840 Speaker 1: so you would be able to see what hour it was. 562 00:31:00,920 --> 00:31:03,600 Speaker 1: But that was it. As clocks became more complicated than 563 00:31:03,600 --> 00:31:07,600 Speaker 1: necessity for precision increased, wheels and pinions have to be 564 00:31:07,640 --> 00:31:10,880 Speaker 1: crafted precisely to transmit motion as steadily as possible in 565 00:31:11,000 --> 00:31:14,240 Speaker 1: order for this to work. Now you might wonder what 566 00:31:14,360 --> 00:31:16,920 Speaker 1: happens when the weight that's providing the force to turn 567 00:31:16,960 --> 00:31:20,120 Speaker 1: all this machinery reaches the ground. What happens is the 568 00:31:20,120 --> 00:31:23,040 Speaker 1: whole thing stops. You have to wind the mechanism so 569 00:31:23,080 --> 00:31:25,360 Speaker 1: that the weight is lifted back to the top, creating 570 00:31:25,360 --> 00:31:28,800 Speaker 1: that potential energy necessary for the clocks operation. This it 571 00:31:28,840 --> 00:31:31,160 Speaker 1: is true of other mechanical clocks as well, whether the 572 00:31:31,200 --> 00:31:34,120 Speaker 1: force comes from a suspended weight or a spring. With 573 00:31:34,280 --> 00:31:37,200 Speaker 1: a spring, you have to wind it to increase its 574 00:31:37,200 --> 00:31:39,880 Speaker 1: potential energy before you let go and it starts to 575 00:31:39,920 --> 00:31:43,320 Speaker 1: convert it into kinetic energy. In fact, spring powered clocks 576 00:31:43,320 --> 00:31:48,080 Speaker 1: would emerge before pendulum clocks did. Peter Henline of Nuremberg 577 00:31:48,400 --> 00:31:52,320 Speaker 1: gets the credit for inventing spring clocks. Early in the 578 00:31:52,520 --> 00:31:56,680 Speaker 1: sixteenth century, sometime between fifteen hundred and fifteen ten, hen 579 00:31:56,760 --> 00:31:59,560 Speaker 1: Line would use a coiler metal while entightly to provide 580 00:31:59,600 --> 00:32:03,240 Speaker 1: the potential energy necessary to drive clockwork. The spring would 581 00:32:03,240 --> 00:32:07,160 Speaker 1: have a natural tendency to unwind and assume its normal shape, 582 00:32:07,400 --> 00:32:09,800 Speaker 1: so winding it would build up that potential energy, and 583 00:32:09,880 --> 00:32:13,360 Speaker 1: using an escapement kept the unwinding to a somewhat regular 584 00:32:13,440 --> 00:32:16,680 Speaker 1: series emotions. And as the coil unwinds, the amount of 585 00:32:16,680 --> 00:32:19,520 Speaker 1: force it exerts decreases, which actually meant that a clock 586 00:32:19,640 --> 00:32:23,080 Speaker 1: would start to run more slowly and begin to lose time. 587 00:32:23,160 --> 00:32:24,640 Speaker 1: To get it going again, you have to wind it 588 00:32:24,720 --> 00:32:28,520 Speaker 1: up again. Now, these early clocks weren't exactly the most accurate. 589 00:32:28,520 --> 00:32:31,680 Speaker 1: According to the Anderson Institute, the big ones could be 590 00:32:31,720 --> 00:32:34,480 Speaker 1: off by as much as an hour per day, and 591 00:32:34,560 --> 00:32:37,040 Speaker 1: they only marked the passing of an hour at a time, 592 00:32:37,200 --> 00:32:40,600 Speaker 1: with no indication for smaller increments. Still, it was a 593 00:32:40,600 --> 00:32:43,360 Speaker 1: way to keep track of time that didn't require members 594 00:32:43,400 --> 00:32:45,920 Speaker 1: of the church to track it themselves and then hike 595 00:32:46,000 --> 00:32:47,680 Speaker 1: up to the top of a bell tower and give 596 00:32:47,720 --> 00:32:50,280 Speaker 1: it the old toll. And if you're wondering how they 597 00:32:50,320 --> 00:32:53,280 Speaker 1: told time at night before they had mechanical clocks. It 598 00:32:53,440 --> 00:32:57,480 Speaker 1: usually involved burning something that had a pretty steady combustion rate. 599 00:32:57,800 --> 00:33:00,480 Speaker 1: This included candles that would burn at a pretty steady 600 00:33:00,520 --> 00:33:02,800 Speaker 1: and predictable rate. You'd have to figure out how big 601 00:33:02,800 --> 00:33:04,959 Speaker 1: your candle needed to be and make the wax as 602 00:33:05,000 --> 00:33:07,960 Speaker 1: consistent as you could, and try and keep track that way. 603 00:33:08,000 --> 00:33:09,520 Speaker 1: You would just mark it on the candle, and when 604 00:33:09,520 --> 00:33:11,320 Speaker 1: the candle burned down to a certain amount, you knew 605 00:33:11,360 --> 00:33:13,880 Speaker 1: an hour had passed. It wasn't down to the minute, 606 00:33:13,920 --> 00:33:16,760 Speaker 1: but it served well enough for the chiming of bells. Now, 607 00:33:17,000 --> 00:33:20,640 Speaker 1: in our next part, we're gonna talk about pendulum clocks. 608 00:33:20,640 --> 00:33:22,680 Speaker 1: But before I get into that, one thing I want 609 00:33:22,720 --> 00:33:27,400 Speaker 1: to mention is if the version folio description has completely baffled, 610 00:33:27,440 --> 00:33:31,480 Speaker 1: you do a search for the terms on YouTube, because 611 00:33:31,520 --> 00:33:33,920 Speaker 1: there are lots of illustrations on there that will show 612 00:33:33,960 --> 00:33:36,560 Speaker 1: you exactly what I'm talking about folio. By the way, 613 00:33:36,600 --> 00:33:40,160 Speaker 1: it's spelled fo L I O T, and you can 614 00:33:40,200 --> 00:33:44,680 Speaker 1: see exactly the mechanisms I'm mentioning and see how they 615 00:33:44,720 --> 00:33:48,720 Speaker 1: were able to regulate the turning of gears. And before 616 00:33:48,720 --> 00:33:51,040 Speaker 1: I get into pendulum clocks, I need to take another 617 00:33:51,120 --> 00:34:02,160 Speaker 1: quick break and thank my sponsor the virgin folio. Escapement 618 00:34:02,200 --> 00:34:04,960 Speaker 1: was the dominant method of regulating the motion of mechanical 619 00:34:05,000 --> 00:34:09,160 Speaker 1: clocks for a couple of centuries. But then an Italian 620 00:34:09,280 --> 00:34:12,640 Speaker 1: smarty pants by the name of Galileo Galilei made an 621 00:34:12,680 --> 00:34:16,839 Speaker 1: interesting observation. He discovered that a pendulum takes the same 622 00:34:16,880 --> 00:34:20,400 Speaker 1: amount of time to complete one full swing out and back, 623 00:34:21,320 --> 00:34:23,919 Speaker 1: over and over and over again. The time for one 624 00:34:24,000 --> 00:34:26,960 Speaker 1: complete cycle is what we call a period. So the 625 00:34:27,000 --> 00:34:29,520 Speaker 1: period of a swing remains the same even as the 626 00:34:29,520 --> 00:34:33,600 Speaker 1: pendulum's swing decreases in amplitude. So what do I mean 627 00:34:33,640 --> 00:34:36,080 Speaker 1: by that? Well, if we were working with a pendulum 628 00:34:36,120 --> 00:34:40,480 Speaker 1: mounted on a massless rod or a line uh and 629 00:34:40,680 --> 00:34:44,080 Speaker 1: had a frictionless pivot, then the pendulum is always going 630 00:34:44,120 --> 00:34:47,040 Speaker 1: to return to the same height as its initial release. 631 00:34:47,760 --> 00:34:51,560 Speaker 1: But that's not how the real world works. So let's 632 00:34:51,600 --> 00:34:54,400 Speaker 1: say you tie a rope to the limb of a tree, 633 00:34:55,000 --> 00:34:57,000 Speaker 1: and on the other end of the rope you tie 634 00:34:57,040 --> 00:34:59,440 Speaker 1: a bowling ball, and you get on a step ladder, 635 00:34:59,640 --> 00:35:02,320 Speaker 1: and you're are far enough back so that the line 636 00:35:02,440 --> 00:35:06,080 Speaker 1: is taught between the limb and the bowling ball, and 637 00:35:06,120 --> 00:35:08,720 Speaker 1: you're standing at a certain level. You're holding the bowling 638 00:35:08,760 --> 00:35:11,919 Speaker 1: ball right up to your chin. With the that line there, 639 00:35:12,000 --> 00:35:13,960 Speaker 1: you let go of the bowling ball. And by the 640 00:35:14,000 --> 00:35:17,160 Speaker 1: way I say let go, you don't push the bowling ball, 641 00:35:17,719 --> 00:35:19,960 Speaker 1: but you just let go. Now if you do that, 642 00:35:20,120 --> 00:35:23,160 Speaker 1: is it going to swing back and knock your teeth out? No, 643 00:35:23,840 --> 00:35:27,080 Speaker 1: it won't, And the reason for that is because elements 644 00:35:27,120 --> 00:35:30,800 Speaker 1: like friction and drag are sapping some of the energy 645 00:35:31,080 --> 00:35:35,040 Speaker 1: from the overall system. The returning bowling ball doesn't have 646 00:35:35,120 --> 00:35:38,359 Speaker 1: the same amount of energy that the departing bowling ball had, 647 00:35:38,440 --> 00:35:41,160 Speaker 1: so it doesn't rise up as high as when you 648 00:35:41,239 --> 00:35:45,080 Speaker 1: dropped it, which means you get to keep your choppers. Congratulations, 649 00:35:45,719 --> 00:35:48,799 Speaker 1: go brush your teeth. But even though the bowling ball 650 00:35:48,960 --> 00:35:51,920 Speaker 1: isn't rising up to the starting height of its release, 651 00:35:52,400 --> 00:35:56,320 Speaker 1: the journey of its swing, its period will remain the same. 652 00:35:56,360 --> 00:35:59,719 Speaker 1: That time remains the same, at least for small amplitudes. 653 00:35:59,800 --> 00:36:02,360 Speaker 1: This story is different if you're swinging that sucker really hard, 654 00:36:02,760 --> 00:36:05,960 Speaker 1: But for simple pendulums at small amplitudes, this is true. 655 00:36:06,360 --> 00:36:08,920 Speaker 1: The ball isn't traveling as far on each swing because 656 00:36:09,200 --> 00:36:12,080 Speaker 1: it's losing that energy to friction and drag, but it's 657 00:36:12,120 --> 00:36:16,960 Speaker 1: also not swinging quite as quickly per swing, so it's 658 00:36:16,960 --> 00:36:18,879 Speaker 1: not going as far, but it's also moving a little 659 00:36:18,880 --> 00:36:21,239 Speaker 1: more slowly, and the overall amount of time it takes 660 00:36:21,280 --> 00:36:26,080 Speaker 1: to complete one period remains constant. Now that means if 661 00:36:26,120 --> 00:36:29,359 Speaker 1: you make a pendulum of a precise length, you can 662 00:36:29,400 --> 00:36:33,040 Speaker 1: create a swing of one second. The period of a 663 00:36:33,080 --> 00:36:36,200 Speaker 1: pendulum swing can be expressed as an equation, and the 664 00:36:36,239 --> 00:36:39,760 Speaker 1: period is equal to two times pie times the square 665 00:36:39,880 --> 00:36:45,320 Speaker 1: root of the length of the pendulum divided by gravity's acceleration. Now, 666 00:36:45,440 --> 00:36:48,920 Speaker 1: ignoring for a moment that gravity's acceleration is not uniform 667 00:36:49,040 --> 00:36:52,759 Speaker 1: everywhere on Earth due to several factors that really are 668 00:36:53,160 --> 00:36:56,160 Speaker 1: too complicated for us to get into here, we can 669 00:36:56,200 --> 00:36:59,839 Speaker 1: simplify this to say that a pendulum of nine nine 670 00:37:00,160 --> 00:37:03,839 Speaker 1: millimeters or about thirty nine inches is the right length 671 00:37:03,920 --> 00:37:07,200 Speaker 1: to have a swing period of a second. Now, Galileo 672 00:37:07,280 --> 00:37:10,480 Speaker 1: recognized the potential for pendulums in timekeeping, but he never 673 00:37:10,560 --> 00:37:14,080 Speaker 1: built a clock using one. That honor goes to a 674 00:37:14,160 --> 00:37:18,239 Speaker 1: Dutch scientist named Christian Hygens, who in the mid seventeenth 675 00:37:18,239 --> 00:37:21,600 Speaker 1: century figured it out. He used the oscillation of a 676 00:37:21,600 --> 00:37:25,280 Speaker 1: pendulum to regulate the motions of clockwork in many ways. 677 00:37:25,400 --> 00:37:28,360 Speaker 1: It was similar to the virgin folio design, except instead 678 00:37:28,360 --> 00:37:32,200 Speaker 1: of relying upon a weighted lever and inertia, Hygen's design 679 00:37:32,239 --> 00:37:35,040 Speaker 1: relied on the natural oscillation of a pendulum of an 680 00:37:35,080 --> 00:37:40,040 Speaker 1: appropriate length. So how does a pendulum escapement work. The 681 00:37:40,160 --> 00:37:43,600 Speaker 1: escapement still engages a gear, preventing it from rotating freely, 682 00:37:44,000 --> 00:37:47,359 Speaker 1: and as the pendulum swings, it rocks the escapement so 683 00:37:47,400 --> 00:37:50,480 Speaker 1: that it disengages with the gear, and the gear begins 684 00:37:50,520 --> 00:37:53,759 Speaker 1: to rotate. At the end of the pendulums period, when 685 00:37:53,760 --> 00:37:57,520 Speaker 1: it returns to its starting point, the escapement is locked 686 00:37:57,560 --> 00:38:01,000 Speaker 1: back into position and the whole process start again. But 687 00:38:01,040 --> 00:38:04,240 Speaker 1: I'm sure you're all wondering how the pendulum keeps moving. 688 00:38:04,280 --> 00:38:07,120 Speaker 1: I mean, if it's losing energy with each swing, how 689 00:38:07,120 --> 00:38:09,839 Speaker 1: does it continue more for more than just a few 690 00:38:09,880 --> 00:38:13,640 Speaker 1: seconds without adding more energy to the pendulum. It's eventually 691 00:38:13,680 --> 00:38:15,759 Speaker 1: just going to slow down and stop swinging completely. I 692 00:38:15,760 --> 00:38:17,799 Speaker 1: mean I talked about this with friction and drag. Well, 693 00:38:17,840 --> 00:38:20,799 Speaker 1: Hygen's got around this by designing a gear that would 694 00:38:20,800 --> 00:38:24,799 Speaker 1: give the pendulum a little nudge each time the escapement disengaged, 695 00:38:25,000 --> 00:38:28,920 Speaker 1: so it provides just enough force to counteract dragon fiction friction. 696 00:38:29,440 --> 00:38:32,800 Speaker 1: So it worked. Hygen's initial design was accurate enough to 697 00:38:32,880 --> 00:38:36,080 Speaker 1: keep time within about a minute per day, meaning you'd 698 00:38:36,080 --> 00:38:39,239 Speaker 1: only lose sixty seconds during a day long operation of 699 00:38:39,239 --> 00:38:42,120 Speaker 1: one of his clocks, which was incredible for the time, 700 00:38:42,360 --> 00:38:45,160 Speaker 1: and he improved upon his design within his own lifetime. 701 00:38:45,160 --> 00:38:48,319 Speaker 1: He cut it down to losing only ten seconds per day, 702 00:38:48,320 --> 00:38:50,680 Speaker 1: which is not bad for an entirely new method of 703 00:38:50,719 --> 00:38:57,160 Speaker 1: regulating gear rotation. Pendulums do come with a couple of complications, however, 704 00:38:57,760 --> 00:39:01,160 Speaker 1: so it doesn't matter what the mass of the pendulum is. 705 00:39:01,400 --> 00:39:03,560 Speaker 1: By the way, you don't whatever the bob is at 706 00:39:03,600 --> 00:39:06,320 Speaker 1: the end of your pendulum. That mass can be anything. 707 00:39:06,360 --> 00:39:09,040 Speaker 1: It's that it's immaterial. It's the length of the pendulum 708 00:39:09,080 --> 00:39:11,920 Speaker 1: that's that's important, not the bob, the mass of the bob, 709 00:39:12,640 --> 00:39:15,480 Speaker 1: except that you don't want something so massive that's going 710 00:39:15,520 --> 00:39:19,680 Speaker 1: to cause damage to the clock itself. But that pendulum's 711 00:39:19,719 --> 00:39:22,000 Speaker 1: length is incredibly important. And this is where we get 712 00:39:22,040 --> 00:39:26,200 Speaker 1: into some trouble because of temperatures. Most pendulums are made 713 00:39:26,200 --> 00:39:28,800 Speaker 1: of metal, and metal has a tendency to expand in 714 00:39:28,840 --> 00:39:31,800 Speaker 1: the presence of heat or contract when it gets colder. 715 00:39:32,239 --> 00:39:35,440 Speaker 1: And since the pendulum's period is dependent in part upon 716 00:39:35,520 --> 00:39:40,400 Speaker 1: its length, this poses a problem. A precisely designed pendulum 717 00:39:40,480 --> 00:39:44,640 Speaker 1: might swing it exactly one second per period, but or 718 00:39:44,680 --> 00:39:46,800 Speaker 1: have a period of one second is the more appropriate 719 00:39:46,800 --> 00:39:48,360 Speaker 1: way of saying that. But if the length of that 720 00:39:48,400 --> 00:39:50,839 Speaker 1: pendulum were to change, it would no longer be true. 721 00:39:50,880 --> 00:39:54,160 Speaker 1: The period would be slightly off from a second, and 722 00:39:54,239 --> 00:39:58,239 Speaker 1: that would be enough to cause errors in timekeeping. Clockmakers 723 00:39:58,320 --> 00:40:00,759 Speaker 1: recognize that issue and they try to fix it in 724 00:40:00,840 --> 00:40:04,759 Speaker 1: different ways. The most common way was do you use 725 00:40:04,800 --> 00:40:07,759 Speaker 1: alloys of metals for pendulums. So an alloy is a 726 00:40:07,760 --> 00:40:10,400 Speaker 1: combination of two or more metals, and one of the 727 00:40:10,440 --> 00:40:12,960 Speaker 1: interesting features of alloys is that you can mix together 728 00:40:13,040 --> 00:40:16,880 Speaker 1: metals that have different coefficients of expansion. So if you 729 00:40:16,920 --> 00:40:20,160 Speaker 1: do this carefully enough, you can cancel out the effects 730 00:40:20,239 --> 00:40:23,560 Speaker 1: of temperature to a great deal. So, for example, you 731 00:40:23,560 --> 00:40:27,440 Speaker 1: can use zinc and iron or brass and steel and 732 00:40:27,560 --> 00:40:30,759 Speaker 1: pair them together in this way, and that ends up 733 00:40:30,840 --> 00:40:33,960 Speaker 1: reducing that effects so that the clock can be more 734 00:40:34,000 --> 00:40:37,120 Speaker 1: accurate no matter what the temperature happens to be. For 735 00:40:37,160 --> 00:40:39,960 Speaker 1: a pendulum clock to be really accurate, you have to 736 00:40:40,000 --> 00:40:43,600 Speaker 1: reduce the impact the impulse of the impulse of the 737 00:40:43,719 --> 00:40:47,279 Speaker 1: turning crown wheel. The crown wheel is the element that 738 00:40:47,400 --> 00:40:51,719 Speaker 1: the escapement locks into, so you have to reduce the 739 00:40:51,760 --> 00:40:54,640 Speaker 1: impact of its motion on the pinchul lium itself and 740 00:40:54,680 --> 00:40:57,960 Speaker 1: needs to give just the right impulse to keep the 741 00:40:57,960 --> 00:41:01,080 Speaker 1: pendulum from swinging and no or or less than that. 742 00:41:01,480 --> 00:41:04,759 Speaker 1: Ideally it would be uniform every single time, meaning you 743 00:41:04,880 --> 00:41:08,799 Speaker 1: have very precise distances between pegs on the crown so 744 00:41:08,840 --> 00:41:11,920 Speaker 1: that it's impact on the escapement would remain consistent no 745 00:41:11,960 --> 00:41:15,560 Speaker 1: matter where it is in the crown wheels rotation. There 746 00:41:15,600 --> 00:41:18,920 Speaker 1: was a guy named Edward Beckett who later on would 747 00:41:19,200 --> 00:41:22,560 Speaker 1: be lorded and would be known as Lord Grimthorpe, which 748 00:41:22,640 --> 00:41:26,480 Speaker 1: is possibly the coolest title I've ever seen. He invented 749 00:41:26,480 --> 00:41:30,560 Speaker 1: what was called the double three legged gravity escapement, which 750 00:41:30,640 --> 00:41:34,840 Speaker 1: honestly sounds like a routine you'd see at Sercla, but 751 00:41:35,080 --> 00:41:38,040 Speaker 1: in fact it was a particular arrangement that allowed for 752 00:41:38,120 --> 00:41:42,360 Speaker 1: extremely consistent operation. He used it to build an enormous 753 00:41:42,400 --> 00:41:47,040 Speaker 1: clock over at Westminster. The clock is world famous, and 754 00:41:47,160 --> 00:41:50,120 Speaker 1: actually people generally call it by the name of the 755 00:41:50,200 --> 00:41:53,560 Speaker 1: huge bell that is also in that clock tower, and 756 00:41:53,600 --> 00:41:55,920 Speaker 1: people just called the whole thing by the bell's name. 757 00:41:56,200 --> 00:42:00,160 Speaker 1: That bell's name, by the way, is Big Ben I 758 00:42:00,239 --> 00:42:04,560 Speaker 1: would describe to you how his escapement works, but I'm 759 00:42:04,600 --> 00:42:07,719 Speaker 1: pretty sure my brain would melt as I tried to 760 00:42:07,760 --> 00:42:11,439 Speaker 1: do this without the use of visual aids. Fortunately, there 761 00:42:11,480 --> 00:42:15,879 Speaker 1: are videos about the double three legged gravity escapement on 762 00:42:15,960 --> 00:42:19,799 Speaker 1: YouTube that show exactly how this works, and it is fascinating. 763 00:42:19,840 --> 00:42:22,839 Speaker 1: I I it really drives home the fact that engineers 764 00:42:23,239 --> 00:42:26,759 Speaker 1: are remarkable people who are way smarter than I am, 765 00:42:27,120 --> 00:42:29,560 Speaker 1: and I highly recommend you go and check these videos 766 00:42:29,560 --> 00:42:33,200 Speaker 1: out to get an appreciation for the actual clockwork that 767 00:42:33,320 --> 00:42:37,080 Speaker 1: makes the regulation possible. And that pretty much wraps up 768 00:42:37,120 --> 00:42:40,160 Speaker 1: this episode of tech stuff. But there's a lot more 769 00:42:40,160 --> 00:42:42,880 Speaker 1: to talk about with watches and clocks. I'm sure in 770 00:42:42,920 --> 00:42:46,640 Speaker 1: a future episode I'll tackle things like quartz watches, which 771 00:42:46,680 --> 00:42:51,040 Speaker 1: rely upon the peculiar piezo electric qualities of quartz, and 772 00:42:51,080 --> 00:42:53,880 Speaker 1: I'll talk about other types of time keeping, things like 773 00:42:53,920 --> 00:42:57,279 Speaker 1: atomic clocks and how those work. But for now, I'm 774 00:42:57,320 --> 00:43:00,640 Speaker 1: going to say it's time to conclude this episode and 775 00:43:00,680 --> 00:43:03,760 Speaker 1: remind you the next time you look at a clock, 776 00:43:04,280 --> 00:43:06,719 Speaker 1: think about all the amazing work it took to make 777 00:43:06,760 --> 00:43:10,640 Speaker 1: it all work out properly. From physics to mathematics to 778 00:43:10,800 --> 00:43:17,000 Speaker 1: engineering to craftsmanship. A clock represents lifetimes of genius, so 779 00:43:17,120 --> 00:43:20,000 Speaker 1: take some time to appreciate it. If you guys have 780 00:43:20,040 --> 00:43:22,800 Speaker 1: suggestions for something I should cover in a future episode 781 00:43:22,800 --> 00:43:25,080 Speaker 1: of tech Stuff, or maybe there's a guest you would 782 00:43:25,120 --> 00:43:26,680 Speaker 1: like me to try and book on the show for 783 00:43:26,719 --> 00:43:29,720 Speaker 1: an interview, or a guest host to talk about specific topic, 784 00:43:30,200 --> 00:43:32,480 Speaker 1: let me know. Send me a message. The email for 785 00:43:32,520 --> 00:43:35,840 Speaker 1: the show is text Stuff at how stuff works dot com, 786 00:43:35,960 --> 00:43:38,080 Speaker 1: or you can always drop me a line on Twitter 787 00:43:38,320 --> 00:43:40,759 Speaker 1: or Facebook. The handle for both of those is tech 788 00:43:40,800 --> 00:43:44,520 Speaker 1: Stuff hs W. Remember we've got an Instagram account. You 789 00:43:44,520 --> 00:43:47,840 Speaker 1: can see all sorts of cool and interesting tech related 790 00:43:47,880 --> 00:43:50,719 Speaker 1: images that Crystal has been posting to that, so check 791 00:43:50,800 --> 00:43:54,160 Speaker 1: that out. And of course I record this show on 792 00:43:54,200 --> 00:43:57,719 Speaker 1: Wednesdays and Fridays, and typically I live stream it. If 793 00:43:57,760 --> 00:44:00,160 Speaker 1: I am doing it on my own, it's to is 794 00:44:00,200 --> 00:44:01,880 Speaker 1: to be live streamed. And if you want to watch 795 00:44:01,920 --> 00:44:06,360 Speaker 1: me while I record a show warts and all, you 796 00:44:06,400 --> 00:44:09,920 Speaker 1: can tune in to twitch dot tv slash tech Stuff. 797 00:44:09,920 --> 00:44:12,200 Speaker 1: There's a chat room in there you can participate in that, 798 00:44:12,640 --> 00:44:14,799 Speaker 1: and whenever I take a break, I'm happy to chat 799 00:44:14,880 --> 00:44:17,239 Speaker 1: with all of my fans in there and uh and 800 00:44:17,320 --> 00:44:20,120 Speaker 1: answer any questions. Sometimes you guys point out things that 801 00:44:20,200 --> 00:44:23,880 Speaker 1: I need to address, like maybe I gave an explanation 802 00:44:24,000 --> 00:44:25,719 Speaker 1: that was a little too vague and I should go 803 00:44:25,800 --> 00:44:28,759 Speaker 1: back and sussed out a bit more. And I really 804 00:44:28,800 --> 00:44:31,279 Speaker 1: appreciate it because it means that the podcast everyone gets 805 00:44:31,360 --> 00:44:33,319 Speaker 1: ends up being better as a result. So you guys 806 00:44:33,320 --> 00:44:35,480 Speaker 1: can help me out if you like, or just hang 807 00:44:35,520 --> 00:44:37,719 Speaker 1: out and make jokes. That's also cool. I have no 808 00:44:37,800 --> 00:44:40,680 Speaker 1: problem with that Twitch, dot tv, slash tech stuff. Hope 809 00:44:40,719 --> 00:44:43,680 Speaker 1: to see there, and I'll talk to you again really 810 00:44:43,719 --> 00:44:51,480 Speaker 1: soon for more on this and thousands of other topics 811 00:44:51,520 --> 00:45:00,520 Speaker 1: because it staff works dot com eight