ORIGIN AND DEVELOPMENT OF THE FROSCH LAMP

Above: Roman open oil lamp, with an open reservoir, made of clay, Raedts collection, object number 004106 Below: Roman open oil lamp, with a closed reservoir, made of terracotta, Raedts collection, object number 004114 © Nederlands Mijnmuseum

The Frosch lamp is an example of an open oil lamp. The first open oil lamps date back to Roman times. The Romans made small bowls from terracotta or clay, in which (animal) fat or wax could burn. A wick was placed in the bowl. The oil or fat was absorbed by the wick, creating a flammable vessel that served as a source of light and heat.

The first more modern Frosch lamps started being produced around 1700. The fragile terracotta or clay bowls were replaced by metal bowls made of iron or brass. This increased the lamps' lifespan and reduced their vulnerability.

From the mid-1800s onward, Frosch lamps were made safer. Instead of an open oil or fat reservoir—where the flammable fat could easily spill—the lamps were fitted with sealed oil reservoirs. The fuel also changed from (animal) fat to oil derived from plants and/or minerals.

Lamps with an open flame were well suited for types of mining (ore) where no gases were present. Open flames combined with mine gas—which can be found in coal mining—posed a dangerous and potentially deadly explosion risk. In coal mining, these lamps were generally used during shaft sinking, including in the Netherlands. When shafts are being sunk, work takes place in solid rock where no coal seams or mine gas are yet present. Therefore, a lamp with an open flame could be used safely in that phase.

By around 1900, the Frosch was no longer commonly used. In ore mining, carbide lamps were introduced at that time. These burned cleaner, were less dangerous, and provided better and stronger light output. By then, the Frosch lamp (in its modern form) had served as a light source for a good 200 years.

_{(Börkel,Werner; Woeckner, Horst: Des Bergmanns Geleucht, IV. Band, Essen, 1983)}