ch all matter has been exhausted.

Vibrator. Mechanism for making and breaking circuits in
induction coils or other apparatus.

Volt. The unit of electro-motive force.

Voltage. Electro-motive force which is expressed in volts.

Voltaic. A term applied to electric currents and devices.

Volt-meter. An apparatus for showing the difference of
potential, or E. M. F. in the term of volts.

Watt. The unit of electrical activity. The product of
amperes multiplied by volts.

Watt Hour. One watt maintained through one hour of time.

Waves, Electric Waves in the ether caused by electro-magnetic
Magnetic. disturbances.

X-rays. The radiation of invisible rays of light, which
penetrate or pass through opaque substances.

Yoke, or Bar. A soft iron body across the ends of a
horseshoe magnet, to enable the magnet to retain its
magnetism an indefinite time.

Zinc Battery. A battery which uses zinc for one of its elements.

INDEX

A

Accumulated, 31.

Accumulation, 29.

Accumulator cell, 87.

Accumulators, 82, 88, 89.

Accumulators, plates, 83.

Acid, 34, 37, 125.

Acid maker, 125.

Acid, sulphuric, 31, 84.

Acidulated, 55.

Acidulated water, 34.

Acoustics, 110.

Actinic rays, 184, 185.

Actinium, 186.

Active element, 82.

Adjustable rod, 107.

Adjusting screw, 70, 71, 72, 73, 106.

Aerial wire, 108.

Agents, 13, 32.

Alarms, burglar, 11, 76, 80.

Alkali, 125.

Alkaline, 37.

Alternate, 127.

Alternating, 38, 149, 150, 153, 154, 155, 156.

Alternating current, 145.

Alternating periods, 149.

Alternations, 147.

Aluminum, 128, 129, 135, 137.

Aluminum hydrate, 129.

Amber, 5, 171.

Ammeter, 7, 88.

Amperage, 38, 61, 62, 132, 159, 160, 168.

Ampere, 7, 37, 60, 63, 139, 140, 167.

Amplitude, 111.

Annunciator, 65, 74, 76, 79, 80, 81.

Annunciator bells, 11.

Anode, 35, 133, 134.

Antennae, 108.

Antimony 137, 143.

Anvil, 13, 14.

Apparatus, 11, 57, 106, 139, 145.

Arc, 163, 182.

Arc lighting, 38, 165.

Arc system, 166.

Armature, 18, 25, 38, 40, 42, 43, 45, 46, 47, 48, 53, 55, 70, 72, 73,
74, 90, 93, 112, 151, 152, 155, 163, 176, 177, 178, 179, 180.

Armature brush, 48.

Armature post, 71.

Armature, vertical, 75.

Arm