lectric unit is the volt-ampere, often called the watt. (Sec Energy, Electric.)
Adapter. A screw coupling to engage with a different sized screw on each end; one of the uses is to connect incandescent lamps to gas-fixtures.
A. D. C. Abbreviation for Anodic Duration Contraction, q. v.; a term in electro-therapeutics.
Adherence, Electro-magnetic. The adherence between surfaces of iron due to elcctro-magnetic attraction. It has been applied to the driving-wheels of an engine and rail, whose grip is increased by such action. In one method a deep groove was cut around the wheel which was wound with a magnetizing coil. Thus one rim becomes a north and the other a south pole, and the rail completing the circuit acts as the armature. Such an arrangement prevents a wheel from sliding. Electro-magnetic adherence has also been employed to drive friction gear wheels. In one arrangement the two wheels are surrounded by a magnetizing coil, under whose induction each attracts the other, developing high