Dowsing is a type of divination employed in attempts to locate ground water, buried metals or ores, gemstones, oil, gravesites, and many other objects and materials, as well as so-called currents of earth radiation (ley lines), without the use of scientific apparatus. Dowsing is also known as divining (especially in reference to interpretation of results), doodlebugging (particularly in the United States, in searching for petroleum) or (when searching specifically for water) water finding, water witching or water dowsing. There is no scientific evidence that dowsing is effective. A Y- or L-shaped twig or rod, called a dowsing rod, divining rod or witching rod is sometimes used during dowsing.