En kavl, eller en fløt, blir brukt til å holde fiskeredskaper som garn, line og not flytende. Kavler kan være av tre, never, bark, glass, kork eller plast. Source: Wikipedia
“Glass floats, glass fishing floats, or Japanese glass fishing floats are popular collectors’ items. They were once used by fishermen in many parts of the world to keep their fishing nets, as well as longlines or droplines afloat.
Norway was the first country to start production and use of glass fishing floats around 1840, many of which can still be found in local boathouses. Christopher Faye, a Norwegian merchant from Bergen, is credited for their invention. The glass float was developed through cooperation with one of the owners of the Hadeland Glassverk in Norway, Chr. Berg.
The first time these “modern” glass fishing floats are mentioned is in the production registry for Hadelands Glassverk in 1842. The registry shows that this is a new type of production.
The earliest evidence of glass floats being used by fishermen comes from Norway in 1844 where glass floats were on gill nets in the great cod fisheries in Lofoten. By the 1940s, glass had replaced wood or cork throughout much of Europe, Russia, North American, and Japan. Japan started using the glass floats as early as 1910. Today, most of the remaining glass floats originated in Japan because it had a large deep sea fishing industry which made extensive use of the floats; some made by Taiwan, Korea and China. In Japanese, the floats are variably known as ukidama (浮き玉?, buoy balls) or bindama (ビン玉?, glass balls).
Glass floats have since been replaced by aluminum, plastic, or Styrofoam.” Source: https://en.wikipedia.org/wiki/Glass_float