In 1900 Joshua Lionel Cowen started the Lionel model-train company, which eventually brought him fortune and fame. But before that, while still in his teens, he walked away from another lucrative business. In the 1890s Cowen invented several devices that could be powered by the newly available dry-cell batteries. One was a fuse for igniting photographic flash powder. The Navy ordered 24,000 of them to use as detonators for underwater mines. Another, as described in The New Yorker in 1947, was “a slender battery in a metal tube, with a light bulb on one end and a switch on the other—an assemblage that, according to the best sources, added up to the world’s first flashlight. For some reason, Cowen overlooked the simplest use of this invention and secreted his flashlights in potted plants, where, when turned on, they would illuminate the flowers.”

Cowen was far from the first person to hook up a light bulb to a battery. The Acme Electric Light Company manufactured battery-powered bicycle lights and hand lanterns in the 1890s. The introduction of comparatively compact “D” cells— the same size as those used today—led to a proliferation of electric novelty items, including scarf pins with small light bulbs concealed inside decorations such as jack o’ lanterns and Santa heads.

The basic form of the flashlight seems obvious and intuitive today, but designers of early portable electric lights were heavily influenced by old technology. Many of their devices looked like candlesticks, candleholders, or lanterns. Owen T. Bugg, Jr., almost got it right in 1898 with his “portable electric lamp,” marketed as the O. T. Bugg Friendly Beacon Electric Candle. The cylindrical battery case remained upright, like a candle, but Bugg mounted the lamp on the side, so the device looked something like a beer stein with a headlight.

Cowen claimed that converting his electric flowerpots into something more practical was his own idea, but other accounts credit Conrad Hubert, an early customer of Cowen who ended up going into business with him. At the time, the government was issuing patents for many variations on the basic idea of a battery-powered light, and “it seemed every day Conrad Hubert and I were suing four people and having four people sue us for patent infringements,” Cowen recalled in the 1950s. “I got disgusted with the whole thing.” He sold the business to Hubert for a token fee.

Hubert then hired an inventor named David Misell, who in 1895 had patented a battery-powered table decoration, a lamp that flickered on and off when wound with a key. He may already have been working on a flashlight in 1897 when he joined Hubert’s American Electrical Novelty and Manufacturing Company. The device described in Misell’s 1899 patent is instantly recognizable: a hollow tube with a small incandescent bulb and reflector at one end and two or more dry cells stacked end to end inside. Pressing on a ring closed the circuit, lighting up the bulb.

You had to keep your thumb pressed down to keep the bulb lit. This was a feature, not a bug. Early dry cells held a meager charge that would be quickly depleted by the power-hungry carbon-filament bulbs of the day, so the “electric hand torch” wasn’t designed for continuous operation. Users were supposed to turn it on for a few seconds at a time, perhaps while rummaging in a dark cupboard for candles and matches, and so it came to be known as a “flash light.” Hubert sold it under the name Ever Ready, which was later shortened to Eveready.

To promote the product, Hubert distributed flashlights to New York City police officers and collected their testimonials. An 1899 advertisement in Electrical Age magazine warned would-be competitors that Hubert was enforcing his company’s patents. Another early advertisement boasted that the Ever Ready Flash Light “gives from 6000 to 8000 lights before the battery requires renewal.”

In the opening years of the twentieth century, the combination of improved battery life and more efficient bulbs using tungsten filaments led to flashlights that could be turned on and left on. In 1906 the National Carbon Company paid $200,000 for a half-interest in Hubert’s company, which by then was called the American Ever Ready Company. (Back in 1896 National Carbon had introduced one of the first dry cells for the consumer market, the six-inch, three-pound Columbia.) The company saw flashlights as a terrific way to generate demand for batteries. Eight years later National Carbon bought Eveready outright for two million dollars.

Adjustable-beam flashlights go back at least to the 1920s. They allowed the user to raise or lower the bulb within the parabolic reflector, moving it toward or away from the focal point to concentrate or diffuse the beam. Today buyers can choose from a bewildering variety of sizes, features, and configurations, but the typical low-cost household flashlight isn’t much different from what Eveready offered in the 1920s. The most significant change has involved not the light itself but the power supply. Alkaline batteries, available since the 1950s, last considerably longer than their zinc-carbon counterparts.

Conventional flashlight bulbs still have tungsten-alloy filaments, but new generations of flashlights use light-emitting diodes to offer vastly greater efficiency than incandescents, which emit 95 percent of their energy in the form of heat. Higher-end flashlights today sometimes employ faceted or textured reflectors, which partially scatter the light, reducing or eliminating the dark holes and rings that occur when you shine a wide beam against a surface.

By the 1970s many customers saw the general-purpose flashlight as essentially disposable, less valuable than the batteries inside (today you can buy packs of AA alkaline batteries that include a small flashlight as a freebie). Countering this perception is the popular Maglite, introduced in 1979 by Mag Instrument. Initially marketed to police departments and other public-safety entities, the rugged and stylish Maglite appealed to consumers as something worth keeping, with the heft and glamour of a weapon. Sometimes it actually is a weapon; the original Maglite was designed to perform double duty as a truncheon.

Military contractors have been developing rugged, high-performance flashlights at least since World War II. Today’s “tactical” models are waterproof and can withstand bomb explosions, tornadoes, and being run over by tanks. They are bright enough to be used for signaling from several miles away. Consumer flashlights based on military models come with such refinements as laser light sources and xenon-filled bulbs, along with various attachments and accessories. One boasts that it is “bright enough to temporarily blind and disorient a person by impairing his night-adapted vision” and features a “crenellated strike bezel” for “enhanced self-defense capabilities.” The most powerful tactical flash-lights sell for close to $5,000 at retail, so there’s no telling what the military pays for them.

Today you can even buy flashlights that don’t require batteries. Freeplay Energy, for example, markets flashlights and other products that use a hand crank to feed current to a battery via an alternator. The Angstrom A2 Fuel Cell Flashlight will shine for up to 24 hours on a full tank of fuel, but bear in mind that most convenience stores don’t stock compressed hydrogen.