The Writer's Almanac with Garrison Keillor

Today marks the autumnal equinox in the Northern Hemisphere, the first day of fall and the point in which the sun is directly above the equator and the hours of day and night are nearly equal. In the Southern Hemisphere, today marks the vernal equinox, the first day of spring.

It's the birthday of British chemist and physicist Michael Faraday, born in south London in 1791. His father was a blacksmith and couldn't afford a formal education for his son, so young Faraday delivered newspapers and then went to work as a bookbinder's apprentice at the age of 14. He had learned to read and write in Sunday school, and now, surrounded by books, he educated himself in his spare time. For seven years he read books on various subjects — mainly science — and when he was 20, he happened to receive tickets to a lecture series by the famous chemist Sir Humphry Davy. So impressed by the lectures was Faraday that he wrote to Davy and asked him for a job. There were no openings at that time, but Davy gave him a job as his lab assistant the following year. And although Davy discovered the elements of sodium, potassium, and calcium (among others), it's often said that Faraday was Davy's greatest discovery.

When Davy retired in 1827, Faraday took over his position as a chemistry lecturer at the Royal Institution. Throughout his life, he continued to give lectures, believing it was important to educate the general public on advances in science. He also began a series of Christmas lectures for children through the Royal Institution in 1825. The lectures have continued every year, with a brief hiatus during World War II when it was unsafe for children to come into London. They are now broadcast on television throughout the United Kingdom, and are as much a part of British Christmas tradition as the queen's speech.

Although he started out in chemistry, it's for his work with electricity that Faraday is most famous. He had dabbled in the study for a while, but he began researching electricity and magnetism in earnest in 1821. Building on the work that others had done with magnetic fields, Faraday transformed electrical energy into mechanical energy, inventing the first electric motor. In 1831, he wrapped an iron ring with two separate wire coils, and found that passing an electrical current through one wire also resulted in a current passing through the second wire. He further discovered that passing a magnet over the coils generated an electrical current. The experiment eventually resulted in "Faraday's law of electromagnetic induction," and the principle is still used today in electric transformers and generators. He also combined the study of electricity with the study of chemistry, proving that, with enough electric force, he could disturb the bonds holding molecules together and cause them to interact in new ways. He also discovered that some substances tended to act as either "conductors" — through which electrical current can flow freely — or "insulators," which are highly resistant to the flow of current. Faraday, in the course of his work, coined now-familiar terms like "ion," "cathode," and "electrode."

On this day in 1953, the world's first four-level interchange opened in Los Angeles, California, linking the freeways of Harbor, Hollywood, Pasadena, and Santa Ana. Nicknamed "The Stack," the interchange boasted 32 lanes of continuous traffic moving in eight directions at once, replacing the slower, more popular cloverleaf design of the time. Designed to let motorists merge without braking, The Stack became an object of awe, fear, derision, and inspiration. The L.A. Times called the 5.5 million-dollar interchange "the most photogenic pile of cement in town" and the "fanciest whip-de-do of bridges."

Featured in fiction and film, The Stack appears in Thomas Pynchon's novel The Crying of Lot 49, Joan Didion's Play It As It Lays, and serves as the backdrop for an alien invasion in the 1953 film The War of the Worlds. Designed by a team of engineers and built by the James I. Barnes Construction Company, the bridge is considered a design landmark by the Society of Civil Engineering. Its distinctive, coiling architecture is a symbol of Los Angeles's post-World War II development, immortalized in countless postcards from the '50s and '60s. Its construction displaced 4,000 residents of Bunker Hill, a historic neighborhood novelist Raymond Chandler once said was populated by "old men with faces like lost battles." Today, Dodger Stadium sits over the rubble of Bunker Hill. In 2006, the interchange was officially renamed the Bill Keene Memorial Interchange, in honor of a beloved local traffic and weather reporter.

It's the 90th birthday of British novelist Rosamunde Pilcher (books by this author), born Rosamunde Scott in Cornwall, England (1924). The author of 27 books — romance novels and popular women's fiction — Pilcher is best known for her 1985 The Shell Seekers, a worldwide best-seller that described what it was like to live in Britain during WWII. Its success helped her 14 grandchildren go to college, but it didn't change her life "stupidly," as she said, with mink coats or Rolls Royces.

It was on this day in 1862 that President Lincoln issued the Emancipation Proclamation, declaring slaves in rebel states free as of January 1 the following year. The war was not going well, and the emancipation of the slaves was meant to build morale in the North. Lincoln waited for a Union victory before he announced it. The Union Army beat back the Confederates at Antietam, the bloodiest single day of the war. Five days later, on this day in 1862, Lincoln read the Emancipation Proclamation to his Cabinet. By the end of the war, more than 500,000 slaves had fled to freedom behind Northern lines. About 200,000 black soldiers and sailors, many of them former slaves, served in the armed forces. They helped the North win the war.

On this day in 1776, Nathan Hale was executed for espionage. Before he was hanged, Hale stood on the gallows and uttered his famous last words: "I only regret that I have but one life to lose for my country."