Mechanical Effects of Discharge

— The discharge of electricity from a conductor is influenced somewhat by the shape of the terminals when the discharge takes place. An electric machine capable of giving a long spark when the knuckle is presented to the knob, will, on fastening a needle to the conductor, discharge the electricity so effectually at its point that only very short sparks can be drawn at the knob, while a fine brush or jet of pale blue light will appear at the poini. An air current is set up of sufficient intensity to blow aside the flame of a lighted candle when brought near. The air current’can be felt by the hand and is due to a mutual repulsion between the electrified ajr particles near the point and the electricity collected on the point itself.