"A balanced-arm lamp, sometimes called a floating arm lamp, is a lamp with an adjustable folding arm which is constructed such that the force due to ...
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gravity is always counteracted by springs, regardless of the position of the arms of the lamp. Many lamp brands (such as the Anglepoise, originator of the concept, and Luxo L-1) as well as other devices, such as drawing boards, use this principle." - (en.wikipedia.org 02.01.2022)