These two circuits are so adjusted that the closed oscillation circuit, consisting of the condenser, primary coil 1 See German Patent of F.
The receiving arrangement consists of an antenna which is connected to earth through the primary coil of an oscillation transformer and a variable inductance.
The primary coil carried the magnetizing current; the secondary, which was wound inside the other, could be connected either with a ballistic galvanometer for determining the induction, or with a Wheatstone's bridge for measuring the resistance, whence the temperature was calculated.
His transmitter consists of a nearly closed oscillating circuit comprising a condenser or battery of Leyden jars, a spark gap, and the primary coil of an oscillation transformer consisting of one turn of thick wire wound on a wooden frame.
Instead of inserting the sensitive tube between the receiving antenna and the earth, he inserted the primary coil of a peculiar form of oscillation transformer and connected the terminals of the tube to the secondary circuit of the transformer.
Such an oscillation valve was first used by Fleming as a receiver for wireless telegraph purposes in 1904 as follows: - In between the receiving antenna and the earth is placed the primary coil of an oscillation transformer; the secondary circuit of this transformer contains a galvanometer in series with it, and the two together are joined between the external negative terminal of the carbon filament of the above-described lamp and the insulated platinum plate.