Electrical oscillation

“ We find that when we set up an electrical oscillation in an open circuit consisting of two metallic rods placed in one straight line, we have proceeding from this circuit an electrical radiation which is capable of being propagated through space, which moves in straight lines, can be reflected and refracted, can exhibit the phenomena of interference, and moreover which is propagated with exactly the same velocity as light. ”

“ If an electrical oscillation is sent through this exceedingly fine platinum wire, it heats it and rapidly increases its resistance. The electrical oscillations produced in an aerial are sent through a number of these loops arranged in parallel, and the loops are short-circuited by a telephone, joined in series with a source of very small electromotive force produced by shunting a single cell or opposing to one another two cells of nearly equal electromotive force. ”

“ You have already seen that an alternating current in one electric circuit can produce another alternating current in a secondary circuit placed parallel with the first. It is not difficult to show, either experimentally or from theory, that when the primary current is an electrical oscillation—that is, a very rapid alternating current—the current in the secondary circuit is also an electrical oscillation of the same frequency or rapidity, but that the currents in the two circuits, primary and secondary, are always moving in opposite directions at the same moment. ”

“ This electrical discharge, or oscillation, is carried by the aerial into the upper air and causes intense pulsations in the ether, which set up waves as already mentioned. If the circuit is opened again the disturbance ceases. So, by alternately closing and opening the circuit, the Morse characters can be imitated.
But how can these signals be received by the man for whom they are intended, who may be a hundred miles or more away? ”

“ It may therefore be compared with a pendulum of any kind which when displaced oscillates with a time period depending on its inertia and on its restoring force.
The study of these electrical oscillations received a great impetus after H.R. Hertz showed that when taking place in electric circuits of a certain kind they create electromagnetic waves (see Electric Waves) in the dielectric surrounding the oscillator, and an additional interest was given to them by their application to telegraphy. ”

“ In addition to its ability to originate 'natural vibrations' when its electrical equilibrium is disturbed, Stone says that an electrical circuit is also 'capable of supporting what are termed forced vibrations' when electrical oscillations elsewhere created are impressed upon it. ”

“ From the electrical condenser the charge is released in the form of a series of electrical oscillations, and in the air wave producing appliance, the compressed air is released in the form of a series of intermittent puffs or blasts. In the electrical wave producing apparatus, these electrical oscillations in the condenser circuit are finally made to produce other oscillations in an air wire or open circuit, just as the puffs of air finally expend themselves in producing aerial oscillations in the siren tube. ”

“ To sum up, we may then say that whenever rapid electrical oscillations are created in open circuit, such as the two rods above described, the arrangement constitutes a device for creating an impulse or effect in the surrounding space called an electric wave in the æther or electro-magnetic medium; just as an organ-pipe or piano-string or other musical instrument constitutes a device for creating waves in the air by means of mechanical oscillations. ”

“ These oscillations, coming to the metallically-coated ends of the glass tube, produce in the interior corresponding electrical oscillations, which set the molecules and atoms of the enclosed rarefied gases into violent commotion, causing them to vibrate at enormous rates and emit those radiations which we know as light. The gases are not rendered incandescent in the ordinary sense, for if it were so, they would be hot, like an incandescent filament. As a matter of fact, there is very little heat noticeable, which speaks well for the economy of the light, since all heat would be loss. ”

“ We have already seen that when two insulated conductors are placed with their ends very near together, and are then electrified, one positively and the other negatively, and then allowed to be suddenly connected by an electric spark, they constitute an arrangement called an electrical oscillator. ”

“ It is a familiar fact that if we time our blows, we can achieve that which no single blow, however powerful, can accomplish in throwing into vibration a body such as a pendulum, which is capable of oscillation under the action of a restoring force. Precisely the same is true of an electric circuit. We have already seen that the receiving aerial has an alternating electromotive force set up in it by the impact of the successive electric waves sent out from the transmitter. ”

“ Christie are also mentioned by Noad, who quotes from Oersted’s treatise on “Thermo-Electricity” the statement of the Danish philosopher “that the most efficacious excitation of electricity upon the earth appears to be produced by the sun, causing daily evaporation, deoxidation and heat, all of which excite electrical currents.” ”

“ A similar effect is produced when reversed undulatory currents are employed as shown in fig. 14, where the current is produced by the vibration of permanent magnets M M ́ in front of electro-magnets (e e ́) , united upon a circuit without a voltaic battery. It will be understood from figs. 13 and 14 that the effect of transmitting musical signals of different pitches simultaneously along a single wire is not to obliterate the vibratory character of the current as in the case of intermittent and pulsatory currents, but to change the shapes of the electrical undulations. ”

“ In one the body of a person was subjected to the rapidly-alternating pressure of an electrical oscillator of two and a half million volts; in the other a small incandescent lamp was lighted by means of a resonant circuit grounded on one end, all the energy being drawn through the earth electrified from a distant transmitter. ”

“ At still higher voltages corona spreads to further distances from the conductor and a greater volume of air becomes luminous. Incidentally, it produces noise. Now to produce light requires power and to produce noise requires power. Air is broken down and is heated in breaking down, and to heat also requires power; therefore, as soon as corona forms, power is consumed or dissipated in its formation. When this phenomenon occurs on the conductors of an alternating current circuit a change takes place in relation to current and voltage. ”

“ The apparatus, oscillator and resonator, being immersed in air, or other discontinuous medium, there occurs—as I have pointed out in the description of my recent experiments before the English and French scientific societies—dissipation of energy by what I think might be appropriately called electric sound waves or sound-waves of electrified air. ”

“ If we administer a blow to a suspended pendulum we have seen that, if left to itself, it vibrates in a definite period of time, called its natural period. In the same manner, if we have a condenser or Leyden jar having electrical capacity which is joined in series with a coil of wire having electrical inertia or inductance, and apply to the circuit so formed a sudden electromotive force or impulse, and then leave the circuit to itself, the electric charge in it vibrates in a certain definite period, called its natural electrical periodic time. ”

“ In our chapter on wireless telegraphy we saw that the discharge of a Leyden jar takes the form of a number of rapid oscillations backwards and forwards. These oscillations take place at a rate of more than half a million per second, but by the use of an apparatus called a “high frequency transformer” the rate is increased to more than a million per second. Electricity in this state of rapid oscillation is known as high frequency electricity, and high frequency currents are very valuable for some kinds of medical work. ”

“ If the oscillatory spark is photographed on a revolving plate or a rapidly moving film, we have evidence in the photograph that such a spark consists of numerous intermittent sparks gradually becoming feebler. As the coil continues to operate, these trains of electric discharges take place at regular intervals. We can cause a train of electric oscillations in one circuit to induce similar oscillations in a neighbouring circuit, and thus construct an oscillation transformer or high frequency induction coil. ”

“ You will notice, however, that the oscillations of the air in the [214] pipe in the air-vessel experiment depend essentially upon the fact that air is a substance which has inertia, or mass, and you will naturally ask what is it which has inertia, or its equivalent, in the electrical experiment? The answer to this question is as follows: Every electric circuit has a quality which is called inductance, in virtue of which an electric current cannot be started in it instantly, even under any electromotive force, and conversely when the current is started it cannot be immediately brought to rest. ”

“ In order to vibrate these heavy parts with the aid of our aetherial oscillations we have to amplify the available current, and during this process we naturally spoil the detail, or, in other words, we magnify it so much that electrical distortions occur through the whole range of various transformers and other items sold by every shop in the world—at double their value. ”

“ An educated American, I claimed, should find no difficulty in understanding the action of a simple mechanism which an uneducated Serbian peasant boy understood.
The Hertzian electrical oscillator, described above, acts like the tuning-fork. The process of pulling apart the two charges, the positive from the negative, and of forcing them to the surface of the spheres by the action of the electrical machine, is a parallel to the process of deflecting by the pressure of our fingers the prongs of the tuning-fork from their normal position. ”

“ When electric oscillations are set up in an open or closed electric circuit having capacity and inductance, and left to themselves, they die away in amplitude, either because they dissipate their energy as heat in overcoming the resistance of the circuit, or because they radiate it by imparting wave motion to the surrounding ether. ”

“ Broadly, the different applications of principles of electricity which have been suggested, group themselves about the common idea, that great electrical disturbances are set up by the sun’s action in connection with the vaporization of some of the matter of the nucleus, and that the tail is probably matter carried away, possibly in connection with electric discharges, under an electrical influence of repulsion exerted by the sun. ”

“ The longer you make your inductance, the greater will be your wave. This means, if you have a great many long leads connecting the condenser, spark gap, and oscillation transformer, you will build up the wave and will lose energy in the long conductors instead of centering it in the primary of your oscillation transformer. ”

“ By varying the frequency of the currents and carefully observing the potential of the insulated body and watching for the disturbance at various neighboring points of the earth's surface resonance might be detected. Should, as the majority of scientific men in all probability believe, the period be extremely small, then a dynamo machine would not do and a proper electrical oscillator would have to be produced and perhaps it might not be possible to obtain such rapid vibrations. ”

“ If this portion of electrified air could be kept still, the electrified body would retain its charge, if not on itself at least in its neighbourhood, but the charged particles of air being free to move under the action of electrical force, tend to move away from the electrified body because it is charged with the same kind of electricity. The charged particles of air therefore tend to move off in the direction of the lines of force and to approach those surrounding bodies which are oppositely electrified. ”

“ When the spark gap and tuning coil of your set are properly adjusted, the needle will swing farthest to the right over the scale and you will then know that the aerial wire system, or open oscillation circuit, and the closed oscillation circuit are in tune and radiating the greatest amount of energy. ”

“ The electrical glow is therefore produced by the constant passage of electricity through a small portion of air in which the tension is very high, so as to charge the surrounding particles of air which are continually swept off by the electric wind, which is an essential part of the phenomenon.
The glow is more easily formed in rare air than in dense air, and more easily when the point is positive than when it is negative. This and many other differences between positive and negative electrification must be studied by those who desire to discover some thing about the nature of electricity. ”

“ I propose to seek for the period by means of an electrical oscillator, or a source of alternating electric currents. One of the terminals of the source would be connected to earth as, for instance, to the city water mains, the other to an insulated body of large surface. It is possible that the outer conducting air strata, or free space, contain an opposite charge and that, together with the earth, they form a condenser of very large capacity. In such case the period of vibration may be very low and an alternating dynamo machine might serve for the purpose of the experiment. ”