Reporter's Statement of the Case 113 C. Cls. damped oscillatory discharge. The frequency of the oscillatory discharge is dependent upon the impedance and capacity of the spark-plug circuit, and its damping, or time that the oscillations decay to zero, is dependent upon the resistance of the circuit.1 18. The entire period of each ignition pulse, which includes these three phases, is of extremely short duration, being measured in terms of microseconds. Each ignition pulse is sequentially distributed to the spark plug in each cylinder of the engine. If the engine is of the customary four-cycle type there will be one ignition pulse per cylinder for every two revolutions of the engine. Thus, in an eightcylinder automobile engine operating at 1,800 R. P. M. (revolutions per minute) or thirty revolutions per second, ignition pulses will be produced at a rate of 120 per second. In a nine-cylinder airplane engine running at this same speed there would be 135 ignition pulses per second. The high frequency component of the ignition pulse (c) acts to generate electromagnetic waves which will be radiated from the various elements of the ignition system, and any adjacent radio receiving antenna will pick up such waves, which will produce a click in the audio output of the receiver for each ignition pulse. With engines operating at the speeds just referred to, these clicks will follow each other so closely that a low-pitched buzz will occur which will interfere with any other signals that are being received. 19. In aviation it is customary to use a high-tension magnetó as a source of energy for the ignition system instead of a battery. In so far as the present case is concerned, the function and operation of the magneto system is similar to that just described in connection with a battery system. 1 A mechanical analogy of (a), (b), and (c) might be typified by a pendulum. Pulling the pendulum slowly to an elevated position at one side would be representative of the initial charging of the capacity by the unidirectional current. Releasing the pendulum would typify the initial breakdown or ionization of the gap. The pendulum would then swing back and forth with a periodicity depending upon its length, and which would typify impedance and capacity effects of the circuit, and the oscillations of the pendulum would gradually decay and the same come to rest due to the resistance of the medium in which it was moving. One microsecond equals one millionth of a second. 595 Reporter's Statement of the Case THE PATENT IN SUIT 20. The specification indicates that the invention relates to electric transmission lines in general but more particularly to lines of high voltage. The patent in suit lists in its specification two objects or purposes. The first object stated is to arrange the lines in such a manner that all accidents from shocks, caused by contact with bare conductors, are avoided. The second object relates to the transmission or reception of radio signals without interference from other electric lines. The patentee summarizes this second object in the following statement: In this manner a radio instrument, for example, may be operated close to the ignition line on an automobile. The patentee initiates his detailed description of his invention in the specification by the following example: Considering an ordinary air line, such as a trolley line for instance, in which the circuit from an electric power source includes a wire carried on poles, as one conductor, and the ground constitutes the other conductor. If now the wire should break and contact with a body standing on the ground, said body will experience a shock when the current passes therethru, and this shock may be fatal as many thousands of volts may be carried over the wire. Taking now the same example and supposing that one of the conductors, the ground, could be slit open and wrapped around the other conductor, the wire, but without touching the latter, then an ideal condition would prevail, where it would be perfectly safe to touch the ground or negative conductor even if the positive conductor or wire should be broken and contact with the negative conductor, because the latter protects the former so that the positive conductor cannot be reached from the outside. Now the present invention aims at creating this ideal condition, practical solutions of which being described in the following description and illustrated in the accompanying drawing. Roporter's Statement of the Case 113 C. Cls. Three drawings are used to illustrate the preferred embodiments of the invention and are reproduced herewith. 21. Fig. 1, which is referred to as showing a general application of the invention to any type of electric transmission line, shows two chambers enclosed on all sides and either lined with a good conductor such as copper, or, in lieu of the lining, constructed entirely of metal. A copper-lined or metal tube 12 physically and electrically connects the two chambers. The chamber on the left-hand side of this figure is referred to 595 Reporter's Statement of the Case as the primary or sending chamber and is stated to contain any kind of electric generating mechanism. This device, as shown in Fig. 1 for the purposes of illustrating the invention, is a direct current dynamo, the same being shown with its negative terminal connected to the lining or metallic walls of the enclosed chamber, and its positive terminal connected to an insulated wire or transmission line passing concentrically through the annular metallic tube connecting the two chambers. The specification states with respect to a ground connection, that There is absolutely no necessity for a "ground" with the earth since all the electric energy is confined within the space enclosed by the negative, metallic conductor, that is to say, the lining of the chambers 10, 11 and the tube 12. The right-hand chamber contains a receiving instrument which may be any kind of electrical device for utilizing electrical energy supplied to it from the particular kind of generator located in the left-hand enclosure. The negative pole of the receiving instrument is connected to the lining or shell of the metallic enclosure and its positive pole is connected to the wire passing concentrically through the metallic tubular member. In operation of the device, electric current flows from the positive pole of the generator through the enclosed concentric wire to the receiving instrument and returns to the generator through the lining of the right-hand chamber, the metallic tube joining the chambers and the connection existent between the wall of the left-hand metallic chamber and the negative terminal of the generator. 22. The modification disclosed in Fig. 2 shows the application of the invention to an ignition system. The ignition system shown for the purposes of disclosure is of the battery type. Its component parts such as the battery, high-tension spark coil, and a timer for controlling the operation of the coil, are enclosed in the left-hand chamber, which the specification again indicates is either metallic or copper-lined. The enclosure for the ignition generator is connected to the negative or return pole of the same. 838936 49 -44 Reporter's Statement of the Case 113 C. Cls. 23. A metallic or copper-lined tube extends from the chamber containing the ignition system to the spark plug and encloses the normally exposed porcelain end of the conventional spark plug and is electrically connected to the outer metallic shield of the plug. The tube thus forms a return path back to the ignition generator. Concentrically mounted in the tube and leading to the insulated terminal of the plug is an insulated high-tension lead for the electrical energy flowing from the ignition system to the plug. 24. A single spark plug is shown, with reference to which the specification states The spark plug is preferably insulated as at 41 from the cylinder walls. The element 41 is an insulating bushing screwed into the engine cylinder and threaded to receive the outer metallic shell of the spark plug. A metal screen covers the interior end of the spark plug within the engine cylinder and is intended to act as a shield for any electrical radiations that might be thrown off by the spark gap at the plug. The ignition system as disclosed in Fig. 2 is not electrically connected to any metallic portion of the engine and is therefore nongrounded, and the tubular member surrounding the high-tension ignition lead therefore constitutes the only return path for the electrical energy from the plug. 25. (a) A metallic surface resists the penetration of electromagnetic waves therethrough and if thick enough forms an effective shield for them. (b) A high frequency current tends to flow on the outer portion of a conductor, its depth of penetration becoming less as the frequency increases. This is known as the "skin effect." Due to this and the capacity effect between the concentric spark plug lead and the surrounding tube or shield, the radio frequency component of the high-tension current flowing to the plug will tend to return on the interior surface of the tube. Therefore, due to both (a) and (b) and dependent upon the thickness of the tube and the tightness of the joints in |