The life and work of Sir Jagadis C. Bose / by Patrick Geddes.

  • Patrick Geddes
Date:
1920
Catalogue details

Licence: In copyright

Credit: The life and work of Sir Jagadis C. Bose / by Patrick Geddes. Source: Wellcome Collection.

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    oscillation was next lucidly imaged by Kelvin, as the swing of ' the electric pendulum.’ But is the energy of these electric oscillations simply dissipated through resistance, and into heat, as in the incandescent particles of the spark we see ? Maxwell had predicted that there must also be some such radiation for electric waves ; so here arises an experimental test between his theory and preceding ones, by which no such phenomenon had been imagined, or is even possible. Here then is where at length Hertz came in, soon with decisive experiments. First he had to devise a fresh apparatus for exciting the oscillating discharges more steadily and more rapidly (a shortened electric pendulum, as it were), and with the discharges more fully under observation and control. In this he succeeded, but not without great difficulties, traced especially to the uncertain and irregular behaviour of the brass balls between which the oscillating discharge took place. But next, how was he to know whether the electric waves, which Maxwell had foreseen, and which he was seeking for, were really being projected into space from his radiator’s oscillating dis¬ charge, or no ? Here, obviously, he needed some kind of receiver for the anticipated rays ; and to contrive it was a new and perplexing experimental problem. His method was to place in the path of the expected rays an exploring apparatus—a pair of closely approximated metallic rods, in which the rays should induce an electric tension ; which should then, when strong enough, give minute sparks between its adjacent poles. Alas! no spark could be observed ; yet Hertz was not discouraged. Realising that such induced currents must needs be extremely small, he had recourse to the microscope. The poles could thus be brought to within a minute distance ; and then he had the joy of success, for a minute but unmistakable spark now appeared with every impulse from the exciting apparatus at some distance off. Here, then, in this tiny spark was at once the success of the primary experiment so long needed
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