Futility Closet - 042-The Balmis Expedition: Using Orphans to Combat Smallpox

Episode Date: January 19, 2015

(Image: Wikimedia Commons) In this episode of the Futility Closet podcast we'll tell how Spanish authorities found an ingenious way to use orphans to bring the smallpox vaccine to the American colonies in 1803. The Balmis Expedition overcame the problems of transporting a fragile vaccine over a long voyage and is credited with saving at least 100,000 lives in the New World. We'll also get some listener updates to the Lady Be Good story and puzzle over why a man would find it more convenient to drive two cars than one. Sources for our segment on the Balmis expedition: J. Antonio Aldrete, "Smallpox Vaccination in the Early 19th Century Using Live Carriers: The Travels of Francisco Xavier de Balmis," Southern Medical Journal, April 2004. Carlos Franco-Paredes, Lorena Lammoglia and José Ignacio Santos-Preciado, "The Spanish Royal Philanthropic Expedition to Bring Smallpox Vaccination to the New World and Asia in the 19th Century," Clinical Infectious Diseases, Nov. 1, 2005. Catherine Mark and José G. Rigau-Pérez, "The World's First Immunization Campaign: The Spanish Smallpox Vaccine Expedition, 1803-1813," Bulletin of the History of Medicine, Spring 2009. John W.R. McIntyre, "Smallpox and Its Control in Canada," Canadian Medical Association Journal, Dec. 14, 1999. Pan-American Health Organization: The Balmis-Salvany Smallpox Expedition: The First Public Health Vaccination Campaign in South America (accessed Jan. 18, 2015). Listener Roger Beck sent these images of the memorial and propeller from the Lady Be Good in Houghton, Mich.: And listener Dan Patterson alerted us to ladybegood.net, an impressive and growing repository of information about the "ghost bomber," including the recovered diaries of co-pilot Robert Toner and flight engineer Harold Ripslinger and some ingenious reconstructions of the lost plane's flight path after the nine crewmen bailed out. This week's lateral thinking puzzle was submitted by listener David White, who sent these corroborating links (warning -- these spoil the puzzle). You can listen using the player above, download this episode directly, or subscribe on iTunes or via the RSS feed at http://feedpress.me/futilitycloset. Please consider becoming a patron of Futility Closet -- on our Patreon page you can pledge any amount per episode, and all contributions are greatly appreciated. You can change or cancel your pledge at any time, and we've set up some rewards to help thank you for your support. You can also make a one-time donation via the Donate button in the sidebar of the Futility Closet website. Many thanks to Doug Ross for the music in this episode. If you have any questions or comments you can reach us at [e-mail]. Thanks for listening!

Welcome to Futility Closet, the celebration of the quirky and the curious, the thought-provoking and the simply amusing. This is the audio companion to the website that catalogs more than 8,000 curiosities in history, language, mathematics, literature, philosophy, and art. You can find us online at futilitycloset.com. Thanks for joining us. Welcome to episode 42. I'm Greg Ross. And I'm Sharon Ross. In 1803, Spain needed a way to carry the fragile smallpox vaccine to its colonies in the New World. In today's show, we'll learn about the Balmas Expedition, a bold plan to transport the vaccine across the Atlantic using 22 orphan boys.

We'll also get some listener updates to last week's story about a lost World War II bomber and puzzle over why a man would find it more convenient to drive two cars than one. bomber and puzzle over why a man would find it more convenient to drive two cars than one. The Balmas Expedition was an expedition from Spain to the New World in 1803 to bring the newly discovered smallpox vaccine there where smallpox was ravaging the population. I think it deserves to be much better known. I didn't know anything about it really until I started researching it to write a post for Futility Closet last September. It's great both because it's kind of a stirring story of the first big public health intervention in the new world, but also because it shows sort of the ingenious way they went about transporting the vaccine across the ocean, given relatively

primitive technology. I just think it's a great story. Smallpox, I don't have to tell anyone, was a horrible scourge on the whole human race for 12,000 years. It probably emerged around 10,000 BC, somewhere in northeastern Africa, and just plagued the globe ever since. It killed up to 30% of its victims. In the late

1700s, 400,000 Europeans died of smallpox each year. Each year? And a third of the people who survived went blind. Oh, I didn't know that part. It was unknown in the New World until Europeans brought it, like they brought so many things,

and just totally just destroyed the population. It was just a complete disaster. Interestingly, I found out while I was researching this, and I didn't have time to track it down, they know precisely how and when it arrived in the New World. Smallpox was brought to the Western Hemisphere in 1520 by an African slave who was a member of the Spanish expedition led by Panfilo de Narvaez. And I don't know how they know that,

I guess. I don't know how you do epidemiology 500 years later but anyway that's at least the theory about how it how and when it arrived and as i say it was just a complete uh disaster for the whole new world uh its spread was a decisive factor in the defeat of both the aztec and the inca empires it reduced the population of mexico from 25 million to 1.6 million that's crazy uh so So you can imagine when Europe finally developed a vaccine around the turn of the 19th century, they were pleading with Spain to bring it to the new world. I should explain there had been two ways to treat smallpox. Before the vaccine was discovered, smallpox. There was, before the vaccine was discovered, they used a technique called variolation, which meant if I had smallpox and you don't, and we want to find a way to protect you, we can take some material from me, usually a crust from a pustule or something, and have you,

for instance, inhale it, just sort of administer it to you. And if that's done properly, you'll still come down with smallpox, but it'll be a much milder case than you otherwise would have had. You'll be much more likely to survive. You'll have a 2% chance of dying instead of a 30% chance, which is still pretty high. And you'll have a much lower chance of being permanently scarred by it. The problem is it's still smallpox we're messing with. I mean, even if you get through that course safely, you can infect the people around you. I mean, it's just a very dangerous way to go about this. They figured out eventually that if you're going to do this at all, you should inoculate a whole community at one time

or put you in a room somewhere until the whole thing has run its course. But it's still far south of a perfect solution. Yeah, sounds risky. So what Edward Jenner discovered in 1797 is you can do pretty much the same thing using cowpox, which is a much less dangerous illness. If I have cowpox and we transfer some material from a lesion, say, on my arm to your arm, you'll come down with cowpox, your body will sort of wake up, your immune system will, and start to produce antibodies against cowpox.

And those apparently confirm the same benefit against smallpox. So you'll get cowpox, and then when you come out of it, you'll be immune to smallpox. Did people die of cowpox, or was it just a much milder disease? It's much milder. Milkmaids would tend to get it from pustules on cows' udders. He sort of stumbled into this by noticing that. So he called that a vaccine. The word vaccine, interestingly, comes from the word for cow for that reason. And so that began, as soon as he discovered it,

he began to spread it around certainly England and Europe. But in 1802, the Viceroy of Colombia, what was then called New Granada, pleaded with King Charles IV of Spain because they were undergoing a huge epidemic of smallpox in the New World, asking them for help and asking them to send the vaccine. And Charles, as it happened, apart from just wanting to help New Spain, had a lot of personal experience with smallpox. His own brother and sister-in-law had died of it, and other relatives were infected but survived. So he had, from personal experience, a strong animus to help them out, which is great. But the question was, this is only 1802, and it's not at all clear how to get a fragile vaccine all the way across the ocean.

too, and it's not at all clear how to get a fragile vaccine all the way across the ocean. It takes a long time to sail across the Atlantic, and you're traveling into warm climates. There's no such thing as sterile procedures or refrigeration. I mean, they tried different ways of transporting the smallpox vaccine. You could dry it onto silk threads or seal it between glass plates, put it in glass vials or store it on points of quills. But it was just very fragile, and a lot of the time it just wasn't active anymore by the time they got it to the destination. So what they hit on, and this is the ingenious part, was orphans. They put together an expedition that would leave Spain in 1803 to sail to the New World, and they brought with it 22 young boys from the orphanages of

Spain. They were ages between three and nine years. None of them had had cowpox or smallpox before. The reason they did this is that someone had discovered that you could pass the vaccine from arm to arm. So they had these 22 young boys. Shortly before they departed Spain, had these 22 young boys shortly before they departed Spain, they vaccinated two of them. They go through the course of the illness. And at this one window between four to 10 days, they develop pustules on their arms. That's just one of the things that happens. And they discovered that in that window, if we take some lymph, say I have the cowpox, if we take some lymph from my arm and administer it to yours, then I'll pass on out of the window, if we take some lymph, say I have the cowpox, if we take some lymph from my arm and administer it to yours, then I'll pass on out of the window, but you'll start working on it

yourself. The clock starts over again. Right. So they can use the orphans as kind of a human chain. You would then pass it on to the next orphan and it would go down. And all this takes time while the ship is crossing the ocean. So they'd still have a live active vaccine working on someone when they get to the new world. So there's all kinds, obviously this happened today, there'd be all kinds of ethical red flags, but this is 1803 and there really was no alternative. It's amazing they came up with this. Yeah, I just think it's really smart. So that's exactly what they did. They set out in 1803 in a ship called the Maria Pita, and it worked in a nutshell. They crossed the Atlantic and arrived in Puerto Rico, and I'll make a very long story short, took the vaccine to Puerto Rico,

Venezuela, Panama, Chile, Bolivia, the Canary Islands, Colombia, Ecuador, Peru, and Mexico. I should have said this is a very small group. The leader was one of the royal doctors to King Charles. His name was Francisco Javier de Balmis, another physician, a couple, I think three male nurses, and two first aid technicians. But just a very small group of people, plus these orphans to take it through, you know, inoculating about 100,000 people altogether all throughout the New World. It's just amazingly ambitious, especially for such a small group. And while they went, they had also brought on the ship thousands of copies of Atreides explaining how this was all working and how to preserve the serum once they'd had it in each new community, which was exactly what it needed to be done.

And you have to remember, too, since this was the early 19th century, what it needed to be done. And you have to remember, too, since this was the early 19th century, a lot of the territory they had to cross was just unmapped mountains, jungles, and rivers. It was just hard even to get around at all, let alone to introduce yourself to new populations and vaccinate them. Even beyond that, when they finished with the New World, they sailed further west to the Philippines, to Macau, and even to the Chinese city of Canton, where they talked the authorities into letting them vaccinate everyone there who requested it. About 600 people did, which is amazing, even more ambitious than they'd set out to do. And then on the way back, as they passed around Africa, they inoculated most of the population of the island of Santa Elena, which was then an English possession. So as I say, this probably wouldn't happen today, but it was a huge success in terms of a public health effort and could be justified.

Arguably, some writers say on the grounds that these Spanish orphans probably faced a rather bleak future, even if they'd stayed in Spain. probably faced a rather bleak future, even if they'd stayed in Spain. So this way, they come to the New World, perhaps with new prospects, and being vaccinated against smallpox into the bargain. That's true. You could argue. So here are the final numbers. From California to Texas down to Guatemala,

they vaccinated more than 45,000 of the 3 million Mexican inhabitants, over 14,000 in the Antilles, 26,000 in South America, more than 9,000 in the Philippines, and hundreds each in Macau, Canton, and Santa Elena. Altogether, they vaccinated more than 100,000 people in the Spanish colonies. That amazes me that this isn't a better known story because it's such a huge effort, especially at that time. But I certainly hadn't heard about it until I'd started researching it. Edward Jenner, who is the doctor back in England who had discovered the vaccine in the first place,

wrote in November 1806 to a friend of his, I don't imagine the annals of a history furnish an example of philanthropy so noble, so extensive as this. It should be noted that Balmis wasn't technically the very first vaccinator in the Americas. That was either a doctor in Boston or in Newfoundland. The records that have come down to us don't quite allow us to tell which one was first. And after Balmese was done, the disease continued to ravage the New World for at least 100 years

just because they were vaccinating about 100,000 people out of a population of millions. So there's just no way, even for a big expedition, to totally eradicate it. That was just too much to do. But he had started the global eradication of smallpox that would take nearly 200 years. The question that everyone wants to know, or at least the one that I did looking into this, is what happened to the children who had been sort of pressed into service here? And the answer seems to be that there's no consensus, at least not that I can find in the medical literature. I'll give you three different sources who say three different things. One says, he sent back the original 20 orphans taken from La Coruna. That's the orphanage.

However, the nurse that had accompanied them decided to remain with the expedition to care for the Mexican children that would carry on the vaccine. That's one. A second source says, the orphaned children from Spain who had been part of the original expedition stayed in Mexico under the supervision of the Bishop of Puebla. And a third says, at ports along the route to South America and the Philippines,

homes were found for the orphans and more children were brought on board. Thereby, vaccination, quote, girdled the world. So I can't find anyone who says that anything bad befell them, that they died or were... That's just funny. There's like three completely different stories. Yeah. So either there is a consensus that I wasn't able to dig up or just the answer is no one knows what happened to them.

It doesn't seem like anything bad, at least, from what I'm able to tell. So that's the Boblust expedition. I have to add here, there's an interesting postscript just while we're talking about smallpox. At the other end of the history of smallpox, 12,000 years after it appeared on the earth, the very last person in the world to die from smallpox is a British woman named Janet Parker, who fell ill on August 11th, 1978, and didn't realize what she had. She thought she had just a headache, muscle pains, and a rash. But she was diagnosed two weeks later with smallpox. And, in fact, she died the following month.

She was the very last person on Earth to die from it. And it's since been completely eradicated. So the puzzle was how she managed to get smallpox. The last case of it before hers, the last naturally occurring infection was in Somalia in 1977. So it's, at that point, it had been so thoroughly eradicated, even if you'd somehow wanted to set out to get smallpox, it would be hard to do it. Well, it turned out she worked as a medical photographer at the University of Birmingham Medical School, and she worked, her darkroom was on the floor above a lab

where they were working on live smallpox viruses. And it appears that what happens, the virus passed through a service duct to a room where she was making telephone calls. Oh, wow. I know, it's just an awful story. Oh. So a formal prosecution was conducted against the university, which failed, but the head of the medical microbiology department at the university committed suicide,

leaving a note that read, I'm sorry to have misplaced the trust which so many of my friends and colleagues have placed in me and my work. Yeah, that must be a real blow. It's late as 1978 to have your doctor tell you that you have smallpox and then actually to die of it. So that can't happen anymore. In 1980, which is two years after that, the World Health Organization announced that smallpox was the first disease to be eradicated by vaccination efforts worldwide.

And so none of us are in any danger anymore. Unless you happen to work right over a lab. That's right. I suppose I shouldn't say that. Yeah, I think there are still stores of it somewhere. So be very careful where you choose to work. Right. Thanks to everyone who's been contributing to our Patreon campaign to help support the podcast. We're very grateful that so many of you value the show and want to help keep it going.

For those who have pledged $3 a show or more, you can see your name immortalized on our website at futilitycloset.com. Just click on Podcast Supporters in the sidebar. Our $5 and up patrons learned last week what we'd be covering in today's show as they receive an advance notice email. And for our extra generous $20 a show patrons, check your email next week for notice of your special episode, where you'll be able to play along as Greg and I challenge each other to a brain-teasing game.

For more information on our Patreon campaign, go to patreon.com slash futilitycloset or see our show notes for the link. Thanks again to all our contributors. We wouldn't be able to keep going without you. Thanks again to all our contributors. We wouldn't be able to keep going without you. In episode 41, Greg recounted the tragic story of the World War II bomber, the Lady Be Good. Dan Patterson wrote in to tell us about a website, ladybegood.net, that has an analysis of the bomber's last few minutes of flight after the crew had bailed out.

Dan writes, it uses flight simulator software and standard engine out trim procedures from B-24 flight manuals to tie together the flight path and position slash orientation of the wreckage. Dan also writes that the moon was new on April 4th, 1943, so the crew had blessed little in the way of visual cues. The stars above them showed them where the horizon was, but beneath them was jet black. Having driven through Utah under similar conditions, I can attest that it is quite disorienting. The last nail in the coffin was that this was a new crew flying alone, so they had no idea what normal was. That's true. Good point. I don't know how I overlooked the site when I was doing the research. It's a terrific site. Yeah, we hadn't come across it before Dan wrote in to

tell us about it. It's a website which, in its own words, is a repository for online information about World War II's Ghost Bomber. I thought that was an interesting name, the Ghost Bomber. The site is actually quite ambitious in what it helps to curate about the Lady Be Good, although it's still under construction at this time, but several sections are up and contain a wealth of information, including the diaries of co-pilot Robert Toner and technical sergeant Harold Ripslinger, maps of the bomber's flight path and crash area and the cruise movements after leaving the plane, and a very detailed description of the attempts to simulate as accurately as possible the last few minutes of the bomber's flight and then subsequent crash. That's really interesting because the bombardier, John Warafka, jumped out, but his parachute didn't open.

So that leaves a ghastly recording of where they all jumped out of the plane. And obviously, they know where it came to rest. So you should be able to infer how the plane found its way from one spot to the other. Yeah, they have a really detailed analysis of how they tried to work this out as accurately as possible. The site is really worth checking out for anybody who's interested in these kinds of details. They have quite a lot of them there. Also, Roger Beck sent in photos of a memorial

consisting of one of the propellers from the Lady Be Good and a plaque of its history. These are outside the town hall of Lake Linden, Michigan, the hometown of one of the crewmen. So we'll have the photos that Roger sent as well as a link to ladybegood.net in our show notes at futilitycloset.com. And thanks so much to everyone who writes in to us. And if you have any questions or comments for us, please send them to podcast at futilitycloset.com. This week, Greg's going to be solving a lateral thinking puzzle for us.

He's going to have to figure something out, asking only yes or no questions. Okay? Nothing like feeling on the spot here. All right. This week's puzzle was sent in by David White. We've done some of his wonderful puzzles before. Yes, he's sent some good ones. David wrote in and said,

Our family got a real kick out of listening to Greg working through my silent monk puzzle. The confusion about why a German man would possibly be trying to kill an American man he had never met in an Italian monastery was greatly entertaining. I vote for him to solve all my puzzles. All right. But anyway, here is another puzzle. All right. But anyway, here is another puzzle. All the details are made up, but it is based on a true event,

which makes me terribly worried that one of you will know it immediately and solve the puzzle in 30 seconds. But that's the risk of these things. Okay. Let's see what it is. So here's David's puzzle. Daniel is an unmarried man who lives alone. He owns a car that works perfectly well and is driven only by him. However, to make his driving more convenient, Daniel decides to buy another car, just like the one he has, which will also be driven only by him. All right.

Why? Oh, that's the puzzle. Wow. That's the puzzle. Okay. All right. Let me get this straight. Okay.

Daniel is an unmarried man who lives alone. Yes. He owns a car that only he drives. Yes. And he's considering buying a second car. Yes. That only he will drive. Correct.

And you said there's a reason for that? It'll make his driving more convenient. To have two cars. Yes. Is that accurate? Correct. One man owns two cars. Right.

And he's the only one who ever drives them. Yes. And that makes his life more convenient. That makes his life more convenient. Exactly. That's exactly right. And this is true. This is true.

This is based on true events. All right. I like the puzzle. Is his occupation important? No. No? No. I'm off the rails already.

Okay. Is the location important? Yes. The, okay, by location, do you mean, do we mean the country? Yes. Wow. This is a good puzzle. All right, the country.

Is it something to do with the conventions of whether you drive on the left or the right? No. Yeah. That was a really good question. That was a really good question. Um, all right, the country's important. Does it have to do with, do with conventions, metric versus English? No.

Would it help me to figure out which country he lives in? Possibly. Is this involved in more than one country? No. So he doesn't travel. He doesn't go across the border. Correct. That's a good question, too.

Yeah. I want credit for the question. All right. Let's say, does he live in the Western Hemisphere? Yes. Does he live in the United States? No. North America?

Yes. Canada? No. Mexico? Yes. All right. What's his name again? Daniel.

Daniel lives in Mexico. Yes. His occupation is important. Correct. Are there other people involved? Not specific other people, no. And his occupation isn't important? Yes. It's still not important. Is. Are there other people involved? Not specific other people, no. And his occupation isn't important? Yes.

It's still not important. So it's not he's a cab driver or something? I'm not changing my mind on the question. All right, but that has something to do with living in Mexico, but he doesn't cross borders. Correct. Does he use the two cars? Okay, so you say these are identical cars, or they might be? Yeah, they could be very similar to each other.

And maybe it's not his occupation, but does he use these cars for something other than just, say, commuting or driving to the grocery store? Irrelevant. Irrelevant. He just drives two cars. Not at the same time, presumably, but yes. He owns two cars. So you say, the way you posed the question, you said he was considering doing this. Yeah.

Can we assume that he actually did it? Yes, yes. And that it had the outcome that he had hoped for? Well, it said Daniel decides to do it, yes. Okay. Yes. And can we say that he was right? Yes, yes.

So he was satisfied. The outcome was successful, yes. So he was, he found his life more convenient owning two cars rather than one. Exactly. By cars we mean ordinary cars, what I think of as a car, like the one I own. Yes. And he drove them, we mean drove them on roads the way people do. Correct.

Do I need to know where he goes exactly? No. He just drives, he just drives two identical cars on Mexican roads without leaving the country. Correct. Is the fact that it's in Mexico important only because this is a true story and that's where it actually happened to take place? In other words, could this have happened elsewhere? It could potentially have happened elsewhere, but there are reasons why it happened in Mexico. Mexico. Mexico. Is the time period important?

Present day, I mean. So it could have happened today. Yeah. All right. Is his specific identity important? No. He's not some actual person that I would recognize. A Mexican?

Is he Mexican? Yes. And this doesn't have anything to do with conventions of Mexican road travel? I mean, we talked about kilometers versus miles and left versus right hand driving. Is it anything like that? Not really, no. Okay. And you say, is there some pattern to when he drives which car?

Yes! Oh, okay. There's some progress. Okay, so we'll call them car A and car B. Okay. Can I assume that they're completely identical? They could be completely identical. Actually, be more specific.

All right. Are they ordinary cars? Yes. Are they cars you could buy in a dealership like anyone would? Are they ordinary cars? Yes. Are they cars you could buy in a dealership like anyone would? So could he, say, have gone to a car dealership and bought, said, give me two of that one? Give me two identical cars off the assembly line that are that make and model, that are brand new cars?

No? Somewhat. Are they customized in some way? The cars, no. Is Daniel customized in some way? No. I don't want to mislead you I'm not quite sure how to answer your question because it depends on exactly what the gist of it is all right but the answer may be no the answer may be that these aren't just totally stock cars they are stock cars but there is some way in which they differ from each other okay no that's fair all right so what I was starting to ask was you said there is some way in which they differ from each other.

Okay, no, that's fair. All right, so what I was starting to ask was, you said there was some difference in the way he used them. For instance, we'll call them car A and car B. Right. Is it something like he drives car A only on certain days? Yes. All right.

Is there a pattern I need to unearth there? There is a pattern but not a specific pattern. It's not like one's on weekdays and one's on weekends. That's correct. It's not like that. Okay. But it's something like that. He has some, when he gets up in the morning and wants to drive a car, he has some rule for which car he drives. Yes. Can I say that? Yes. Is that because of the destination he's heading to? No. Is it because of the mileage that he wants to record? No. Man, that was another good question. Is it the mileage that he wants to record? No.

Man, that was another good question. Full credit for good questions. Is it something to do with the fuel? No. Do I need to know exactly where he lives or what kind of, where he keeps the cars? No, no. This does take place in a specific place in Mexico. Would that help me to know?

It might. Is it a specific place do you mean the setting like the geography or the no um but i mean as opposed to like does he live near the sea or in the center of the country something like that in the mountains something like that not exactly like that um is there a specific i don't know how to ask that is there like a specific city or yes region of mexico that's what it is um that has some bearing on this yeah is he near the u.s border is he near a border i don't know and that's not relevant okay is he is he near the coast near the sea uh is that important i don't have have real... No, that's not important. It's what city he's in.

What city? Is it Mexico City? It's Mexico City, specifically. This happens specifically in Mexico City. Okay. And it's not a question of where he parks or keeps the car? That's correct. He drives...

Mexico City is very big. Very big and very populous. But you say his occupation isn't important. That's correct. But it's a very populated city. Okay. So he has some rule about which car he drives when. Does he live in Mexico City?

Yes. Can we say that he never leaves Mexico City? We could say he never leaves Mexico City. So he just needs to get around Mexico City and he finds it more convenient to have two cars for doing so. Yes. Are there two systems roads, something like that? No.

Damn, I don't know much about Mexico City. Well, you don't need to know a lot about Mexico City except that it's very densely populated. Does he have passengers when he's driving? No, it doesn't matter. He might not? He might not. And you had about he has a rule, like when he gets up in the morning, he knows which car he's going to be driving. Does that have something to do with traffic then?

Somewhat, yes. So does the rule have something to do with whether the traffic is bad in the direction he wants to head no um okay the rule doesn't have to do with passengers it has to do with i don't know pedestrians no where the route he's going to take no uh and it's not where he's keeping the car what else could it be he's always the one who's driving the car, you said. Yes. It's not someone else. Yes. Yes. And like when he gets up in the morning without consulting anything, he would know which car he was going to drive that day.

So it's not the weather. He would just know. Correct. It's just he says, okay, it's Monday. Yes, exactly. It's Monday, I drive car A. Yeah. It's Tuesday, I drive car A again.

Possibly. He doesn't just alternate them every day. That's Monday, I drive car A. Yeah. It's Tuesday, I drive car A again. Possibly. He doesn't just alternate them every day. That's correct. And it doesn't matter what the specific rule is, but you've got it. It's the day of the week. It's connected to the day of the week. Exactly. And he's...

Is that something to do with... This is a little difficult. No, I feel like I'm making progress. You are making progress. And this would happen in Mexico City. This wouldn't happen somewhere else in the U.S. I mean, it could, but it wouldn't with what obtains these days. When you say it's more convenient, do you mean it saves him time?

Possibly. Saves him money? No. I mean... See what I mean? Yeah. This has to do with because Mexico City is very densely populated. And you said it doesn't have to do with pedestrians or something?

Correct. If he has to go all the way across town, for instance, would that influence his decision of which car to take? No. It's just the day. It's just the day of the week. And I don't need to know. And if he was going to go out of Mexico City, then he could take whichever car he wanted if he's going to be driving somewhere else. This is just if he's driving in Mexico City.

And it's not just a—does it have to do with fuel consumption? No. No. Okay, so he gets up on Monday and he thinks—before he even opens his eyes, his lying bend is, okay, it's Monday. Monday. That means I'll be using car A today. Exactly. He actually does that.

He drives around all day in Mexico City going nowhere in particular. He's just doing his life. Right. Always in car A. Right. Comes home at the end of the day and parks the car next to car B. Right. The next day, he wakes up and does the same thing with car B.

Yes. Let's say. Possibly, yes. Because it's Tuesday. And that's his plan and he's happy with the plan and it actually is working out the way he'd hoped it would. Perfectly, yes. Well, it's working out for him the way he'd hoped it would. It's not working out for Mexico City.

Does it have to do with pollution? Yes, somewhat. But driving two cars, I would think, would pollute just as much. Do I need to know more about the cars? Are they green cars? No, no. You need to know more about Mexico City's... Is it cars? No, no. You need to know more about Mexico City's... Is it smog? I mean,

is it general air pollution? No, no, no, no. Not specifically. Daniel's plan is working out perfectly for him, but it's not working out for Mexico City. And you're saying it has something to do with pollution? Partly. There

must be then laws in mexico city about how many oh i see so he's skirting a law that says that you can't drive one car more than a certain number of miles per no no but you're on the right track there's some law in mexico city intended to reduce pollution pollution and traffic congestion yes that, that limits the amount of driving one person can do. Is that right? Somewhat. Somewhat. Not exactly.

It has to do with the days of the week. Oh, so you can only drive. Is that right? Wow. Are there laws in Mexico City that say that a given person can only drive on certain days of the week? Not a given person. A certain car.

Uh-huh. A certain car with a certain license plate. Yes, that's it. That's exactly it. So he's skirting a law that says you can only drive a car with a given license plate on certain days of the week, so he buys a second car. Right, exactly. This is the answer.

Daniel lives in Mexico City and, like many other residents of that city, has come up with a solution to work around the city's oi no circula driving restrictions. has come up with a solution to work around the city's oi no circula driving restrictions. In 1989, in an effort to reduce traffic congestion and pollution, Mexico City put into place a system intended to reduce the number of vehicles on the road by only allowing certain cars to drive on certain days. The restrictions were based on the last digit of the vehicle's license plate. For example, cars whose license plate ended in a 1 or 2 were prohibited for driving on Mondays. If the license plate ended in a 3 or 4, the vehicle could not drive on Tuesdays, and so on.

So you just bought a second car. Unfortunately, the plan backfired when residents came up with another solution, buy a second car. Right, that's exactly it. By shopping for older cars that still had license plates and selecting one with a different last number on the plate, residents who could afford two cars were able to legally drive every day of the week. As a result, the levels of congestion and pollution did not diminish significantly. That's really good that you got it. That was very complicated, but it was interesting.

That's a really good puzzle, though, especially because that's true. I had no idea that was the case. So thanks so much to David. And if you have a puzzle for us to use, you can send it to podcast at futilitycloset.com. That wraps up another episode for us. If you're looking for more Futility Closet, check out our books on Amazon or visit the website at futilitycloset.com

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