Marconi applied a modified and improved form of Branly's wave detector in conjunction with a novel form of radiator for the telegraphic transmission of intelligence through space without wires, and he and others developed this new form of telegraphy with the greatest rapidity and success into a startling and most useful means of communicating through space electrically without connecting wires.
Denotes radiator V.
To regulate the heat it is necessary either to instal a number of small radiators or to divide the radiators into sections, each section controlled by distinct valves; steam may then be admitted to all the sections of the radiator or to any less number of sections as desired.
Radiators should not be fixed directly on to the main heating pipe, but always on branches of smaller diameter leading from the flow pipe to one end of the radiator and back to the main return pipe from the other end; they may then be easily controlled by a valve placed on the branch from the flow pipe.
To each radiator should be fitted an air tap, which when opened will permit the escape of any air that has accumulated in the coil; otherwise free circulation is impossible, and the full benefit of the heat is not obtained.
A radiator of this last class can be constructed by connecting inductively or directly FIG.
Lodge was, however, fully aware that it was necessary for syntonic telegraphy to provide a radiator capable of emitting sustained trains of waves.
His proposed radiator and absorber consisted of two wing-shaped plates of copper, the transmitter plates being interrupted in the centre by a spark gap, and the receiver plates by an inductance coil from the ends of which connexions were made to a coherer.
He invented for this purpose a radiator consisting of two metal rods placed in one line, their inner ends being provided with poles nearly touching and their outer ends with metal plates.
The ideal radiator is realized within any closed cavity, the walls of which are maintained at a definite temperature.
When we speak of the sun's radiation as a whole, it is assumed that it is of the character of the radiations from an ideal radiator at an appropriate temperature.
If we assume that the bolograph of solar energy is simply a graph of amorphous radiation from an ideal radiator, so that the con- Temperature stants cl, c 2, of Planck's formula determined terrestrially apply to it, the hyperbola of maximum intensity is XO = 2, 921 X 10 7; and as the sun's maximum intensity occurs for about X =4900, we find the absolute temperature to be 5960° abs.
Matter of which the surface is composed is such as to give an ideal radiator; it is impossible to answer this, but even if we admit a departure as great as the greatest known terrestrial exception, the estimated temperature is diminished only some Io %.
Effective temperature, as an ideal radiator or " black body ": 6000° abs.
Xvi.) that, if for the sake of argument the solar atmosphere be taken as homogeneous in temperature and quality, forming a sheet which itself radiates as well as absorbs, the radiation which an unshielded ideal radiator at 6000° would give is represented well, both in sum and in the distribution of intensity with respect to wave-length, by another ideal radiator - now the actual body of ///4, *...