If the antenna or ground connections is loose, or if the ariel or lead in wire is grounded through a branch of a tree, or in some other way, the set will fail to operate. Make sure of good insulation all around. It sometimes happens that a wire will break inside the set box. This generally occurs to one of the wires connecting the secondary induction coils to the various taps to the secondary dial switch. One way to discover this fault is to turn the “Coupling” handle back and forth; the signals may then suddenly stop for a certain position of the handle, although they will be audible with the handle on either side of this position. Finally, a plate of one of the variable air condensers may become warped and short circuit the condenser. This is generally evidenced by the fact that the condenser, when varied over its whole range, does not change the loudness of the signals. In active service, the receiving sets are required to be in continuous working condition. To insure this, spare parts must be kept on hand at all times in order to replace defective parts with the least possible delay. Such spare parts should include spare crystals, telephones and telephone cords. Complete extra set should always be in stock at the central Radio supply station to provide for replacement promptly when sets are destroyed. The sets in use should also be frequently tested to determine and readiness for an intensive and continuous activity. The condenser and inductance circuits should be tested to make sure that each part of each circuit is in perfect working condition. Testing of circuit parts may be simply done with a head phone and dry cell, a click through closed circuits, and the absence of a click through the condenser circuits, being the indication which should be noted. CHAPTER XVI. SMALL ARMS. Notes on the Automatic Pistol, Cal. 45, Model 1911. The pistol is known as the Automatic Pistol, Cal. 45, Model 1911. By caliber is meant the caliber of the bore. All pistols used in the service are marked on the left side of the receiver, “United States Property,” and on the right side with the serial number, which must be memorized by the person to whom the pistol is issued. It is important that every man have a thorough knowledge of the nomenclature, care and repair, method of assembling and dismounting the pistol as well as its use and operation. =The principal parts= of the pistol are the _receiver, the barrel and the slide_.