Lantern

A lantern is a portable lighting device used to illuminate broad areas. Lanterns may be used for signaling, or as general light sources for camping. Dim varieties are often used for decoration.

The term "lantern" is also used more generically to mean a 'light source' or the enclosure for a light source, i.e., the housing for the lamp and lens -- that is the top section -- of a lighthouse. [ [http://www.terrypepper.com/lights/closeups/illumination/index.htm Terry Pepper, "Seeing the Light", Lighthouses of the western Great Lakes, Illumination.] ]

Traditional and decorative lanterns

The simplest technology used is the "candle lantern". Candles give only a weak light, and must be protected from wind to prevent from flickering or complete extinguishment. A typical candle lantern is a metal box or cylinder with glass side panels and an opening or ventilated cover on the top.

Decorative lanterns exist in a wide range of designs. Some hang from buildings, while others are placed on or just above the ground. Paper lanterns occur in societies around the world. Modern varieties often place an electric light in a decorative glass case.

The ancient Chinese sometimes captured fireflies in transparent or semi-transparent containers and used them as (short-term) lanterns. "Raise the Red Lantern", a Chinese film, prominently features lanterns as a motif.

Use of fireflies in transparent containers was also a widespread practice in ancient India. But since these were short term solutions, the use of fire torches was more prevalent.Fact|date=May 2008

Kerosene lantern

The "kerosene lantern", also popularly referred to as a "hurricane lantern" was commonly used from the late 1800s through the middle of the 20th century. A kerosene lantern is a rugged version of a kerosene lamp and is designed for portability. The metal chimney and side tubes, which securely supports the glass globe to prevent breakage, typically contains a ducting system to stabilize and enhance the draft of air reaching the flame resulting in a stable, brighter, wind resistant flame. Lanterns with enhanced drafting are referred to as either "hot blast" or "cold blast" tubular lanterns, depending on their design, with the latter being more common. Large kerosene lanterns produce 12-14 candela of light and approximately 1500 Btu of heat.

Common residential/agricultural applications for kerosene lamps were lighting unelectrified rural homes, barns and the path for nighttime visits to outhouse. Horse drawn carriages, railroad cars, ships, and early automobiles used kerosene lanterns for nighttime illumination, but the brighter carbide lamp was preferred for this use. The kerosene lantern was also heavily used as a method of signaling and navigational marking in railroad, nautical, firefighting, and public works applications. Lanterns used for signaling often had interchangeable globes of different colours. For example, lanterns with red and green globes were placed on the sides of ships to mark port and starboard, while lanterns with clear globes were used to indicate the ship was at anchor. Lanterns designed for marking purposes sometimes had extra large fuel tanks to permit 48 hours of continuous burning to permit workers to leave it unattended over the weekend.

Widespread rural electrification, improvements in battery operated lamps such as flashlights, and the affordability of portable gas-powered mantle lamps, spelled the decline of the kerosene lantern. Today, kerosene lanterns are still manufactured in China, some using the original tooling from the early 1900s. In the United States, antique lanterns are a collector's item, especially lanterns manufactured for carriages, fire trucks and railroads. Most often they are used for decoration and are never lit. The few remaining lanterns actually lit are used as source of emergency light during power outages, or as mood lighting. The Amish, some campers, and some individuals living "off-the-grid" still use kerosene lanterns on a regular basis.

Modern fueled lanterns

All fueled lanterns are somewhat hazardous due to the danger of handling flammable and toxic fuel, danger of fire or burns from the high temperatures involved, and potential dangers from carbon monoxide poisoning if used in an enclosed environment.

Simple wick lanterns remain available. They are cheap and durable, but provide little light and are unsuitable for reading. They require periodic trimming of the wick and regular cleaning of soot from the inside of the glass chimney.

Mantle lanterns use a woven ceramic impregnated gas mantle to accept and re-radiate heat as visible light from a flame. The mantle does not burn (but the cloth matrix carrying the ceramic must be "burned out" with a match prior to its first use). When heated by the operating flame the mantle glows incandescently. Such lanterns are very bright, and can easily be used as reading lights. The heat may be provided by a gas, by kerosene, or by a pressurized liquid such as "white gas," which is essentially naphtha. For protection from the high temperatures produced and to stabilize the airflow, a cylindrical glass shield called the "globe" or "chimney" is placed around the mantle.

Manually pressurized lanterns using white gas (also marketed as "Coleman Fuel" or "Camp Fuel") are manufactured by the Coleman Company in one and two mantle models. Some models are "dual fuel," which can also use gasoline. These are being supplanted by a battery-powered fluorescent lamp models by many manufacturers including Coleman. Liquid fuel lanterns remain popular where the fuel (see portable stove for a discussion on fuel) is easily obtained and is in common use.

A very efficient multifuel lantern has been developed in India which runs on kerosene, diesel and low grade ethanol [http://nariphaltan.virtualave.net/lantern.htm] .

Many portable mantle-type fuel lanterns now use fuel gases that becomes liquid when compressed, such as propane, either alone or combined with butane. Such lamps usually use a small disposable steel container to provide the fuel. The ability to refuel without liquid fuel handling increases safety and additional fuel supplies for such lamps have an indefinite shelf life if the containers are protected from moisture (which can cause corrosion of the container) and excess heat.

The leading manufacture of kerosene mantle lamps in the United States is the Aladdin Mantle Lamp Company, which has long produced an extensive line of utilitarian and decorative mantle lamps. A specialized cylindrical wick with a central airflow tube satisfies the high and uniform heating demands of the mantle.

Modern electric lanterns

Some lanterns are battery-powered and have a simple lightbulb, but bright and efficient electric lanterns will employ a specialized power supply to operate a fluorescent type. They are easy to use and comparatively durable, but less bright than propane or liquid fuel lanterns. Depending on the design, these lanterns may use disposable batteries, rechargeable replaceable batteries, or permanently-installed rechargeable batteries and either require battery replacement, or if rechargeable and not constantly plugged in must be brought to full charge every few months by plugging in.

Some rechargeable fluorescent lanterns may be plugged in at all times and may be set up to illuminate upon a power failure, a useful feature in some applications. During extensive power failures (or for remote use), supplemental recharging may be provided from an automobile's twelve volt electrical system or from a modest solar powered charger. Solar-powered lanterns have become popular in developing countries where they provide a safer and cheaper alternative to kerosene lamps [ [http://www.ashdenawards.org/winners/nest Ashden Awards case study on solar-powered lanterns in India] ] .

Battery-powered lanterns utilizing LEDs are becoming increasingly popular due to improvements in LED technology and reduced production costs. LEDs have become brighter and more rugged, and typically run longer (due to low current draw from the batteries) than incandescent bulbs or fluorescent tubes of comparable brightness.

References

ee also

*Kerosene lamp
*List of light sources