plug while inserting it and pulling it out, the likelihood of breaking the internal connections and wearing out the wires will be reduced to a minimum. Disadvantages of the Monocord Switchboard. 1. It does not afford as quick connections as the by-cords switchboard type. 2. It is not self-contained. A self-contained switchboard includes operators, receiver and transmitter and ringing and night alarm circuits. 3. The operator’s telephone is usually equipped with a hand set, (receiver and transmitter) which leaves him with only one free hand for making connections. 4. One switchboard is equipped with but one master, or operators cord, this affords only one means of answering and calling. Advantages of the Monocord Switchboard. 1. Small, compact, light weight. 2. Simple wiring. 3. Quickly installed. 4. Particularly suited for small central exchanges. 5. Units can be removed quickly, in case of trouble in interior circuits. Any unit can be removed without disturbing other units. Common Faults and Remedies of the Magneto Telephone. The most common trouble in telephone instruments are due generally to one of three causes. (1) Loose or dirty connections at the binding posts of the instrument, at the binding posts of the batteries, or in joints of the line wires, (2) exhausted, poor, or weak batteries, (3) crossed, open, or defective wires. These troubles, of course, do not include those arising from inferior or defective instruments. If the connections are dirty, corroded or greasy, scrape the wires and clean out the binding posts, then screw the wires firmly in place. If the telephone does not then work properly, examine the batteries and see whether they are run down or whether the zincs are eaten away. With wet batteries, it may be possible that the water has evaporated; in dry batteries, the zincs may be eaten through or the batteries may be otherwise defective. The simplest way to test a battery is to try a new battery, and see whether it will make the telephone work properly; if it does, the trouble is with the old battery. If the trouble is present after changing the battery, examine the line connections and the line outside; if any loose connections are found, correct them at once. When inspecting the line outside see that it does not touch anything except the insulators, and that it is neither crossed nor broken. On grounded lines—grounded lines are obsolete now in modern warfare on the account of the many means of detecting and picking up messages now employed; in fact the metallic circuit telephone lines are now used within a mile of the front lines except for messages which would be of no value to the enemy—examine the ground connections the first thing and see whether it is in good condition, and if a plate is used see that it is in moist ground. The frequent trouble with transmitters is the frying noise; that is usually caused by induction or static electricity, and may also be caused by loose connections.