Temistocle Calzecchi-Onesti was born in Lapedona, Italy, on December 14, 1853.
Unfortunately I have been unable to discover much about his family or early life. If I do then this page will be updated.
Temistocle graduated from the University of Pisa in physical and mathematical sciences. He taught in schools until he was named "Professore di fisica del R. Istituto tecnico de L’Aquila", an important technical post in the Institute de L’Aquila, in the December of 1879 .
Temistocle was a physicist and inventor. In his experiments he observed that loosely packed metallic powders are bad electricity conductors until subjected to some external forces such as electric sparks or the presence of inductive fields, or by electrostatic induction.
He demonstrated, in experiments carried out between 1884 and 1886, that metal filings contained in an insulating tube, his "tubetto to limatura", will conduct an electrical current under the action of an electromagnetic wave. This property disappears if the tube is shaken. This phenomenon was used by Branly and by Marconi in the coherer – one of the first receivers of electromagnetic waves used in wireless telegraphy, although Temistocle conceived the device, essentially, in order to reveal the approach of thunderstorms.
(The coherer acts like a kind of semi-conductor device, something like a triac or an SCR, where the trigger is a radio wave instead of a current applied to the gate. When Temistocle subjected the tube to the influence of an electromagnetic field (and such as the radio wave produced by a spark) an electric current can flow from one electrode to the other, probably because of microscopic electric arcs that weld together adjoining metal particles).
Sir Oliver Lodge, who provided the name for the device, explained the principle of the micro-welds in 1890. Edouard Branly devised a device, based upon the work of Temistocle, for inclusion in a receiver, connected to the aerial and acting as an off-on switching device, to detect transmissions. Popov and Marconi, among others, used this device in their early radio experiments.
Temistocle died on November 25, 1922 in Monterubbiano, Italy.
Temistocles' work was important enough for the Italian post office to issue a stamp honouring him in the "First 100 Years of Radio" series in 1995.
