E very home has one — sometimes one in each room — on hand for emergencies. Most toolboxes have one; for plumbers and electricians, it is an indispensable tool for peering into small, dark areas. Every fire truck or emergency services vehicle stocks rechargeable ones. They are also found in cars, on key chains and in toy boxes.

If you haven’t guessed by now, we are talking about the flashlight. The flashlight is a relatively recent invention, but has grown into a must-have gadget for homeowners and builders alike.

Flashlight aficionado Stuart Schneider has thoroughly researched the history of flashlights for several books, including Collecting Flashlights in 1996. “Since the flashlight could not exist without a battery and a bulb, the history of the flashlight is associated with batteries and bulbs,” writes Schnieder, a New Jersey author who has appeared on “Martha Stewart Living” with some of his antique flashlights. “The first battery appeared in 1866, invented by French inventor, George Leclanche. He called it a ‘single fluid electric generating battery.’ It was a wet cell, made by filling a glass jar with ammonium chloride, manganese dioxide and zinc and then adding a carbon bar for the positive end of the cell. It was not portable. If tipped over, the acid would spill out. Thomas Edison invented the incandescent bulb in 1879. Improvement to the battery came in 1888, when a German scientist, Dr. Carl Gassner, encased the wet cell chemicals in a sealed zinc container. This was the first dry cell and the first portable battery.”

The leading name in flashlights was, and is, Eveready. According to About.com, the flashlight was invented in 1898. The story goes that Joshua Lionel Cowen, the original owner of the American Eveready Battery Company, came up with an idea for a decorative lighting fixture for flower pots. It was a metal tube with a light bulb and a dry cell battery that could run the light bulb for 30 days. Electricity from the battery made the flower pot “light up” when a button was pressed — the perfect product for gardeners who wanted to display prize blooms.

To gain recognition they assembled a number of hand torches and gave them to New York City policemen. These testimonials turned into a brilliant marketing strategy; soon everyone wanted a flashlight.

But when Cowen abandoned his CEO duties to become a full-time inventor, he passed this idea (and his company) to one of his sales reps, Conrad Hubert, for a small fee. Hubert, a Russian immigrant, came to the United States in 1890 at age 35. Hubert took Cowen’s idea and, with the help of employee and fellow inventor David Misell, began to adapt it. According to the Energizer Web site, the first flashlights in 1898 were handmade from crude paper and fiber tubes, with a bulb and a rough brass refractor. They called it an electric hand torch.

To gain recognition for their invention, Hubert and Misell assembled a number of hand torches and gave them to New York City policemen. These testimonials turned into a brilliant marketing strategy; soon everyone wanted a flashlight, named for the brief flash of light (similar to a camera) produced by the batteries and bulb.

Misell patented several of his flashlights, and these patents were granted to Hubert’s company. One year later, in 1899, Hubert was awarded with a patent for his clover leaf bicycle light. These two creations, along with 23 other battery/bulb products, were unveiled to the world in the 1899 American Eveready Battery Company catalog with the tagline, “Let There Be Light.”

In 1906, Hubert sold a half interest in his company to National Carbon Company, a supplier of battery materials, for $200,000. Hubert remained president. Later the trade name was shortened from “Ever Ready” to “Eveready.” And National Carbon Company was renamed Energizer in the 1950s.

In 1910, great advances were made in flashlight technology. Tungsten filament bulbs were invented, and replaced carbon filaments in light bulbs. Tungsten bulbs were more efficient and much brighter. According to Energizer.com, vest pocket tungsten flashlights became popular, as did search lanterns, house lamps and intricate art deco candle lamps.

It was the end of an era. No longer did people have to worry about the flame of a candle or kerosene lamp setting their home on fire. According to an Eveready brochure called “101 Uses For An Eveready,” by 1916 the flashlight was an essential personal item — “the light that does not flicker in a draught, extinguish in the wind, and is controlled instantly by finger pressure. It’s the light everyone needs.” Some of the flashlight’s 101 suggested uses included reading fruit labels, filling the tank of a gasoline stove and signaling with Morse Code. The design of the flashlight was also improved, moving from a ring tab that needed pressure to operate to the on/off switch that we use today.

The Eveready Battery Company/Energizer introduced the first 9-volt battery (1956); the first batteries for use in transistor radios and rechargeable nickel-cadmium batteries (1958); the first standard alkaline battery (1959) for longer battery life in portable, battery-powered devices; the first silver oxide button cell for use in miniature hearing aids and watches (1960); and developed lithium battery technology (1963). Today, Energizer is the world’s largest manufacturer of batteries and flashlights, producing more than six billion battery cells annually.

Whatever happened to Joshua Lionel Cowen? Cowen didn’t become an immediate multimillionaire like Hubert, but he went on to invent toy trains in 1900 and started a new company, Lionel Model Trains.