The stethoscope was invented because a doctor felt awkward pressing his ear to a woman’s chest.

In 1816, a French physician named René Laennec found himself in a delicate situation. He needed to listen to the heart of a young female patient but didn’t have an ideal way to do so based on the standard practices of the time. Doctors in the early 19th century relied primarily on touch to assess the heart, pressing their hands to gauge its strength and rhythm. This method often wasn’t reliable, especially, as was the case in Laennec’s situation, if the patient was of a heavier weight. Applying the ear directly to a chest was another approach, but Laennec felt that would be inappropriate and uncomfortable given his patient’s age and gender. 

Laennec also happened to be a skilled musician. Drawing on a basic principle of acoustics — that sound travels better through solid materials than through air — he rolled a sheet of paper into a cylinder and placed one end on the patient’s chest and the other to his ear. The heartbeat came through far more clearly and distinctly than it would have with touch or direct ear contact. Three years later, he published his findings and the first design of a monaural stethoscope, the name of which comes from the Greek words stethos, meaning “chest,” and skopein, meaning “to explore.” 

The device was a simple wooden tube about 10 inches long that carried sound to one ear. The stethoscope marked the start of mediate auscultation — diagnosing conditions by listening to the body’s internal functions. Laennec’s design was used until flexible rubber-tubed binaural models appeared later in the 19th century.

The invention of the leaf blower triggered legal action across the U.S.

The 1970s were an exciting time for suburbanites across the United States. Children plunged themselves into video games with the emergence of arcades and the first home consoles. Microwave ovens made reheating meals a snap. And homeowners could rid themselves of leaves accumulating in their yards sans the usual raking effort with the introduction of the handheld leaf blower. 

During the water shortage that affected California in the latter half of the decade, the machines proved especially popular among Golden State residents who were encouraged to blow debris off their decks instead of hosing them down. But there were a few problems to be tackled with the peace-shattering leaf blower. The San Francisco Bay Area city of Carmel-by-the-Sea even enacted an ordinance in 1975 in which the leaf blower was “declared to be a public nuisance and unlawful.” Soon afterward, the upscale L.A. neighborhood of Beverly Hills also moved forward with a ban due to complaints over noise and dust stirred up by the gasoline-powered machines. By the late 1990s, 20 California cities and an additional 80 across the nation had ordinances that either banned or placed restrictions on the use of leaf blowers.

The pushback prompted manufacturers to develop “quieter” and more environmentally friendly machines, and today, consumers can choose from an array of electric options that release zero emissions and are less likely to put an entire neighborhood on edge. Yet the gas-guzzlers continue to have their proponents, particularly among lawn-care workers who lament the limited power of electric model batteries, ensuring that the fallout over the leaf blower will continue amid the enduring human need to produce the most picturesque yard.

Bubble gum’s color comes from the only dye the inventor had.

It’s often said that necessity is the mother of invention, and when it comes to confectionery, it is indeed the reason for bubble gum’s iconic color. Bubble gum was invented in 1928 by Walter Diemer, an accountant at a Philadelphia candy company called Fleer. Although chewing gum had existed for thousands of years in various forms — such as birch bark resin or chicle, a natural gum from the sap of the sapodilla tree — the products available in the U.S. at the time were more sticky than stretchy. That included an early version of bubble gum (also invented by Fleer) known as Blibber-Blubber, which was hard to chew and stubbornly stuck to people’s faces when the meager bubble inevitably burst.

Diemer spent his downtime experimenting with the company’s gum recipes, and he eventually came up with a more pliable chewing gum that, for the first time, could easily form and hold a bubble. The new formulation was appealing, but its appearance certainly wasn’t — the chewy gray substance needed some color. The only dye Diemer had on hand at the time was red; with no other choice, he added it to his mixture to give it a cheerful tint, and the first batch of pink bubble gum was born. Fleer demonstrated the new bubble gum at a local grocery store and had an immediate hit on its hands. The gum was named Dubble Bubble and inspired a slew of pink copycats — including the famous Bazooka Bubble Gum released just after World War II. 

People hated shopping carts when they were invented in 1937.

During the Great Depression in the 1930s, most Americans were just trying to get by, and few had the luxury of coming home from the grocery store with extra items. But that didn’t stop an Oklahoma grocer from coming up with the idea of a shopping cart, an invention that started out almost as disdained as it was practical.

The man behind the idea was Sylvan N. Goldman, owner of the Humpty Dumpty grocery chain. Interested in increasing his sales, he often paid close attention to how people shopped. One thing stood out: Customers would stop shopping once their handheld baskets got too heavy. Goldman started thinking: What if there were a way for shoppers to carry more with less effort? As an experiment, he took a folding chair, added wheels to the legs, and placed a basket on the seat. He then attached a platform between the chair’s supports to hold a second basket, creating a two-tiered cart that shoppers could push.

When he rolled out these new grocery carts in 1937, he expected a runaway hit, but the reaction wasn’t exactly enthusiastic. Women, already used to pushing strollers, weren’t eager to push another one at the store. Men, on the other hand, preferred not to push something stroller-like at all. To get people on board, Goldman got creative. He hired store greeters to hand shoppers a cart, and even paid actors to walk around shopping with them. Slowly, the idea caught on, and once it did, there was no going back.