SLABY-ARCO MULTIPLE SYSTEM. That the earth which seems so necessary to the successful transmission of electric waves over long dis tances could be employed, Dr. Adolph Slaby and tive wave detector. For this reason high aerial wires are employed, and both oscillator and reso nator are of the open-circuit type. Excellent re sults are assured without regard to the co efficients of the circuits, for in this type of ap paratus the periodicity of the oscillations and the length of the emitted wave may vary con siderably without ally untoward results.
The apparatus shown in Fig. 6 was the first form of wireless telegraph employed by Marconi, and has been found to be the most practical to the present time. All the succeeding systems, whether syntonic or non-syntonic, are modifica tionsof this type.
Count Georg Arco of Germany devised the type of apparatus shown in diagram in Fig. 15, and by photograph on the Plate (q.v.). By math ematical analysis it was determined that if the aerial wire was one-fourth the length of the emitted wave the earth would then become a nodal point. and this being the ease it mast neces sarily follow that a second wire of the same length represented by 2, 3, 4, 5, A, in the diagram will. if a current is set up in it, likewise oscil late in the antenna, 1, 6: with the wave crests at the spark-gap, 2, and the free end of the aerial wire. 1, while the wave valley will be at 6, as graphically shown by the dotted lines. In the resonator. B, the oscillations set up in the antenna are communicated to the horizontal auxiliary wire, having a coherer placed at a point where the amplitude of the wave is great est, as indicated by the dotted lines. In ac cordance with these principles all wave lengths different from those predetermined, and to which the instruments are tuned, will dissipate their energy into the earth, since the earth at 6 no longer becomes the node of the waves.
MAncom SYNTONIC SYSTEM. In combining
open and closed circuits (lughelm° 'Marconi of Italy has employed radically different methods from those adopted in the preceding systems.
This system however, largely based on the ciples of the syntonic jars, and may be said to be an extension of this experimental apparatus.
In the diagram Fig. 16, the general arrange ment of the radiator and resonator is shown. Re ferring to the sending apparatus, 1 A represents an inner metal cylinder connected to the earth at 5; the outer cylinder, 2, is connected to one side of the spark-gap. 3, the opposite side lead ing to the inner cylinder and the earth at 5 through the inductance, 4.
When the spark takes place the current oseil ]ates between the cylinders, emitting a long train of waves baying a low damping factor. The resonator system of the receiver B is similar to the oscillator; the inner cylinder is connected to the earth, while the outer cylinder is connected to earth through the primary of the transformer coil, I', and the inductance, 4'; the secondary of the transformer. 2', is connected with the coherer, 3'. The object of placing the latter in a separate circuit is that the free period of oscillation may not be affected by the high resistance of the colorer. When oscillations are set up in A, waves of a given length are emitted, and these impinging on B up currents of a similar fre quency. the eumnlative action of which breaks down the resis4ance of the eoherer and registers a dot or a dash as the case may he.
In this system a sensitive relay is connected in series with the eoherer; the relay on being actuated closes a second local circuit which in chides a Morse printing register and the tapper used for decohering the filings of the coherer. Fig. 1 on Plate H. shows the apparatus as ar ranged in a station.