TITLE: October 29: Calculus, Crashes, and the Birth of the Internet
October 29 has seen a symbol drawn in a notebook, a stock market collapse, a crashed computer login, and a 77-year-old astronaut returning to orbit. Here are seven of the day's most remarkable moments.
1. 1675 - Leibniz Writes the Integral Sign
On October 29, 1675, the German polymath Gottfried Wilhelm Leibniz was working through problems about areas under curves in his private notes. He needed a shorter way to write "the sum of all these infinitely small pieces," so he stretched out the letter S, for the Latin summa, into the tall, graceful ∫. It was a small change in handwriting that went on to shape how mathematics is written. Leibniz and Isaac Newton each developed calculus independently, which led to one of the bitterest priority disputes in the history of science. Newton's notation was awkward, though, and Leibniz's was clear and flexible. His ∫ and the "d" notation he introduced a few weeks later (as in dx) made calculus easier to teach, share, and extend, and continental European mathematics moved ahead quickly as a result. Every engineering student, physicist, and economist who integrates a function today uses the symbol Leibniz first wrote that autumn day. It is one of the rare cases where we can point to the exact date a piece of mathematical language was invented.
2. 1863 - The Red Cross Movement Is Born
In 1859, the Swiss businessman Henri Dunant came upon the aftermath of the Battle of Solferino in northern Italy, where tens of thousands of wounded soldiers lay with almost no care. He described the scene in his 1862 book A Memory of Solferino and proposed that every nation form volunteer relief societies, trained in peacetime and ready to help the wounded in war. His idea quickly gained support. Delegates from across Europe met in Geneva in October 1863, and on October 29 the conference adopted resolutions that set the framework for national relief societies. These later became the Red Cross and Red Crescent societies, and they adopted the distinctive red cross on a white armband as their emblem. The next year, the first Geneva Convention made protection for the wounded and for medical personnel part of international law. Dunant shared the first Nobel Peace Prize in 1901. Today the movement includes about 190 national societies and millions of volunteers. All of it grew from the belief that a wounded soldier stops being an enemy and becomes simply a person who needs help.
3. 1923 - The Republic of Turkey Is Proclaimed
After the Ottoman Empire's defeat in World War I and the hard-fought Turkish War of Independence that followed, Mustafa Kemal led a nationalist government based in Ankara. On October 29, 1923, the Grand National Assembly formally proclaimed the Republic of Turkey and elected him its first president that same day. The proclamation ended more than 600 years of Ottoman rule. Over the next decade Kemal, who later took the surname Atatürk ("Father of the Turks"), carried out sweeping reforms. He abolished the caliphate, replaced Arabic script with a Latin-based alphabet, adopted Western legal codes, introduced surnames, and extended voting rights to women, ahead of many European nations. October 29 is still celebrated in Turkey as Republic Day, with flags, parades, and fireworks across the country. Historians still debate parts of Atatürk's legacy, but few individuals in the 20th century reshaped a nation so thoroughly in such a short time.
4. 1929 - Black Tuesday
The Roaring Twenties were fueled partly by a speculative stock market boom, much of it financed with borrowed money. Prices had been shaky for days, and on Monday, October 28, the market had already fallen sharply. Tuesday, October 29, was worse. About 16.4 million shares changed hands in a frenzy of panic selling, a record that held for nearly 40 years, and ticker tapes ran hours behind the trading. Billions of dollars in paper wealth disappeared within days. Black Tuesday did not cause the Great Depression on its own, since banking failures, collapsing trade, and policy mistakes all played a part. It did become the symbol of the moment the prosperity of the 1920s ended. The Dow Jones Industrial Average did not regain its 1929 peak until 1954, a quarter-century later. The crash led to lasting reforms, including the Securities and Exchange Commission, federal deposit insurance, and new rules on buying stocks with borrowed money. Many of these safeguards still shape financial markets today.
5. 1945 - The Ballpoint Pen Goes on Sale
Hungarian journalist László Bíró had patented a practical ballpoint pen in the late 1930s, using quick-drying newspaper-style ink and a small rotating ball. American entrepreneur Milton Reynolds saw the design on a trip to Argentina, quickly produced his own version, and rushed it to market. On October 29, 1945, Gimbels department store in New York City began selling the "Reynolds Rocket." Shoppers lined up, and thousands of pens sold on the first day, even at the steep price of $12.50, roughly what a family might spend on a week's groceries. Advertisements promised a pen that could write under water and for years without refilling. Those early pens often leaked, skipped, and smeared, and the fad faded within a few years. The idea survived. Manufacturers such as Bic later refined the design and brought the price down to pennies. The ballpoint became one of the most widely used manufactured objects in the world, and many of its users have no idea it was once a luxury item.
6. 1969 - The First Message Over ARPANET
At 10:30 PM on October 29, 1969, UCLA student programmer Charley Kline, working in Professor Leonard Kleinrock's lab, sat down to log in remotely to a computer at the Stanford Research Institute, about 350 miles away. He typed "L," and SRI confirmed receiving it. He typed "O," which also arrived. When he typed "G," the SRI system crashed. So the first message ever sent over ARPANET, the U.S. Defense Department-funded network that became the Internet, was simply "LO." Kleinrock later joked that it was a fitting first word, as in "lo and behold." About an hour later the bug was fixed and the full login went through. From two connected computers that night, the network grew to four nodes by the end of 1969 and eventually to the billions of devices online today. Email, the web, streaming video, and the screen you may be reading this on all trace back to those two letters sent across California.
7. 1998 - John Glenn Returns to Space at 77
On February 20, 1962, John Glenn became an American hero as the first U.S. astronaut to orbit Earth, circling it three times in the tiny Friendship 7 capsule. He went on to serve 24 years as a U.S. Senator from Ohio, but he never stopped wanting to fly again. On October 29, 1998, at age 77, Glenn launched aboard the Space Shuttle Discovery on mission STS-95. He became the oldest person to fly in space up to that time, a record that stood until the suborbital space-tourism flights of 2021. During the nine-day mission he took part in experiments on how spaceflight affects the aging body, including bone loss, sleep, and balance, which in some ways mirror the effects of growing old. Millions watched the launch, many of them people who remembered his first flight 36 years earlier. Glenn's return showed that age need not limit curiosity or courage. He died in 2016 at 95, still one of the great figures of the space age.
Reflection: The Threads That Bind Us
The events of October 29 range across nearly three and a half centuries, and they are linked in ways that are easy to miss. Leibniz's integral sign led to the mathematics that made computers and spaceflight possible, which in turn made the ARPANET and John Glenn's return to orbit possible. The financial wreckage of Black Tuesday and the humanitarian ideals of the Red Cross both remind us that systems built by people can fail badly, and that people can also build institutions to soften the damage. A new republic, a cheap pen, and a crashed login each show that large changes often start with small, uncertain steps. History is less a list of separate dates than one long conversation across generations. Each time we write with a ballpoint, send a message, or look up at the night sky, we take part in it.