He constructs what he calls a Multiplicator, which is really a wire wound into a loose spiral connected at one point to an oscillation circuit consisting of a condenser inductance, the length of this wire being proportioned so that there is a great resonance or multiplication of tension or potential at its free end.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming
The mode of operation of this receiver is as follows: When the wave strikes the aerial it sets up in it electrical oscillations with a potential antinode at the summit, and at the same time a potential antinode is created at the outer end of the spiral attached near the base of the aerial, this spiral being called by Professor Slaby a Multiplicator.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming