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"When a current is passed through the instrument it causes one end of the movable system to tilt downwards, and the other end upwards; the sliding weight is then moved along the tray by means of a silk cord until equilibrium is again established." —Encyclopedia Britannica, 1910

Lord Kelvin's Ampere Balance

"When a current is passed through the instrument it causes one end of the movable system to tilt downwards,…

"The connexions of all these six coils are such that when a current is passed through the whole of the coils in series, forces of attraction and repulsion are brought into existence which tend to force one movable coil upwards and the other movable coil downwards." —Encyclopedia Britannica, 1910

Connexions of Kelvin Ampere Balance

"The connexions of all these six coils are such that when a current is passed through the whole of the…

"The upper edge of the shelf on which the weights slide is graduated into equal divisions, and the weight is provided with a sharp tongue of metal in order that its posistion on the shelf may be accurately determined." —Encyclopedia Britannica, 1910

Slider of Kelvin Ampere Balance

"The upper edge of the shelf on which the weights slide is graduated into equal divisions, and the weight…