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Today, the term lantern is used to describe many types of portable lighting, but lanterns originated as a protective enclosure for a light source - usually a candle - to make it easier to carry and hang up, and more practical outdoors or in drafty interiors such as passages and staircases where unguarded candles were more likely to be blown out by gusts of air - not just from wind but even opening a door.
Lanterns were usually made from a metal frame, commonly with a hook or hoop of metal on top. Though some lanterns had up to eight sides, five or six was not uncommon but four was the standard, these would be made of some translucent material, now usually glass or plastic but formerly thin sheets of animal horn or tinplate punched with holes or, more ornately, in decorative patterns; though some antique lanterns have only a metal grid, clearly indicating their function was that outlined below.
Though primarily used to prevent the light from being extinguished, their equally important function was to reduce the risk of fire should a spark leap from the flame or the light be dropped. This was especially important below deck on ships, not only because of the common presence of gunpowder but because fire in a warehouse on land would cost money but fire aboard a ship was far more likely to cost lives too.
Use of unguarded lights was taken so seriously that obligatory use of lanterns below decks was even written into one of the few known remaining examples of pirate code - and it is reasonable to assume, given the severity of the punishment and the possible consequences of dropping a naked flame in confined spaces filled with flammable materials, that the use of lanterns was very widely considered an essential safety measure. Note that the term used was "lanthorn", which perhaps has its etymology in the above mentioned use of thinned animal horn as the sheet material in the lantern (article VI of Captain John Phillips's articles).
Lanterns may also be used for signaling, as torches, or as general light sources outdoors. Low light level varieties are used for decoration. The term "lantern" is also used more generically to mean a light source, or the enclosure for a light source. Examples are glass pane enclosed street lights, or the housing for the top lamp and lens section of a lighthouse. The term is commonly associated with Chinese paper lanterns.
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. Lanterns are used in many Asian festivals. During the Ghost Festival, lotus shaped lanterns are set afloat in rivers and seas to symbolic guide the lost souls of forgotten ancestors to the afterlife. During the Lantern Festival, the displaying of many lanterns is still a common sight on the 15th day of the first lunar month throughout China. In other Chinese festivities, the kongming lanterns can be seen floating high into the sky during Chinese festivities. Lanterns are the central theme of the Seoul Lantern Festival, too.
Modern fueled lanterns
All fueled lanterns are somewhat hazardous owing 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 and can also use gasoline. These are being supplanted by a battery-powered fluorescent lamp and LED models, which are safer in the hands of young people and inside tents. Battery-operated lanterns are produced by many manufacturers including Coleman. Liquid fuel lanterns remain popular where the fuel is easily obtained and in common use.
Many portable mantle-type fuel lanterns now use fuel gases that become 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.
Modern electric lanterns
Lanterns designed as permanently mounted electric lighting fixtures are used in interior, landscape, and civic lighting applications. Styles can evoke former eras, unify street furniture themes, or enhance aesthetic considerations. They are manufactured for use with various wired voltage supplies.
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 12-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.
Battery powered lanterns
Various battery types are used in portable light sources. They are more convenient and produce less heat than combustion lights. At least the lower energy density types tend to be safer than fuel use.
Large flashlights of six volts and more have often been called lanterns, even though they produce a directional beam.
The light emitting tubes of fluorescent lights are too big to easily be used to produce a directional beam, but they are several times as efficient as incandescent filament bulbs and are useful for area illumination. They have partly replaced fuel lanterns for camping use, but are now being replaced by more compact and potentially even more efficient LEDs.
Lanterns utilizing LEDs are becoming increasingly popular due to energy conservation, improvements in LED technology, and reduced production costs. Mounted lanterns can use LED lamps in the phase-out of incandescent light bulbs. LEDs have become brighter and more rugged. Battery-powered lanterns typically run longer (due to low current draw from the batteries) than incandescent bulbs do and sometimes than fluorescent tubes of comparable brightness. Some LED lanterns can be powered by USB, solar panel, or even a hand crank. Flashlights can be used as lanterns by diffuse (non-specular) reflection, or by removing the focusing components.
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- Needham, Joseph (1985). Science and Civilisation in China: Paper and Printing. Cambridge University Press. ISBN 978-0-521-08690-5.