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 gravity is always counteracted by springs, regardless of the position of the arms of the lamp. Many lamp brands, as well as other devices, use this principle.
Anglepoise model 1227 from 1935
An upper arm showing three parallel bars
Spring-balanced bending arm lamp
Moving streetlamps in Rotterdam
A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wear and tear on the lifting machine.
César Pelli's Ratner Athletic Center uses cables, masts and underground counterweights as a load-bearing support structure.
Leaning Tower of Pisa has used external counterweights to stabilize the once gradually falling structure.
Counterweight of elevator
Concrete counterweights on a tower crane