By Bruce J. Hunt
Early 1888, Oliver Lodge performed a series of experiments on electrical oscillations along wires that led him very close to Heinrich Hertz’s discovery, announced that same year, of electromagnetic waves in free space. Within a few years, Lodge and others began to use such waves for wireless telegraphy, laying the foundations for technologies that are now ubiquitous. On the surface this looks like a classic case of ‘applied science’, in which a laboratory discovery was turned to practical use, and in some ways it was. But on digging more deeply, we find that Lodge’s work was itself rooted in an intensely practical concern: the protection of buildings from lightning. The path from lightning protection to the discovery of electromagnetic waves, and then on to their use in telecommunications, was winding and indirect. Following this path will shed light on some important ways in which technology and science can interact.
Lodge’s work on lightning grew out of an invitation from the Society of Arts in London that he deliver two lectures on the subject as a memorial to Dr. Robert Mann, a former president of the Meteorological Society. Lodge read up on the subject, particularly the authoritative 1882 Report of the Lightning Rod Conference, and also performed experiments of his own, using tea trays to stand in for storm clouds and discharges from large Leyden jars to mimic bolts of lightning.1 This choice of model was the key to almost all that followed, and it turned out to have some flaws—clouds, it seems, are not really much like tea trays. Simply as studies of Leyden jar discharges, however, Lodge’s experiments were valid and valuable; they shed light on several phenomena related to lightning protection, and more importantly, they led him to new discoveries about rapidly oscillating electric currents.
Many of Lodge’s experiments involved what he called ‘the alternative path’: he would arrange various conductors and insulators, connect them to his Leyden jars, charge them with an electrostatic generator, and see which path the resulting discharge followed. In the course of these experiments, he found many cases, particularly of what he called ‘impulsive rush’, that did not behave the way orthodox theories of lightning protection would have predicted. This led Lodge to criticize some of the conclusions of the Lightning Rod Conference and landed him in heated controversies with some of its defenders. Lodge also noticed some new and unexpected phenomena, particularly when he discharged the Leyden jars into pairs of long parallel wires. Not only did sparks sometimes jump between the wires, but the sparks were longest at their ends, as if the current was surging along the wires and producing a ‘recoil kick’ as it reflected off their ends. Lodge knew that Leyden jars discharges could produce oscillating currents and, partly prompted by his junior colleague A. P. Chattock, he now concluded that these were forming actual electromagnetic waves that were moving at the speed of light through the space surrounding the wires. Here, Lodge thought, was the long-sought confirmation of Maxwell’s theory of the electromagnetic field. He appended a section on these waves along wires to a paper on ‘Lightning Conductors’ that he sent off to the Philosophical Magazine in June 1888, and he set off on a hiking holiday in the Tyrolean Alps with fond hopes that his discovery would be the hit of the upcoming meeting of the British Association, set for September in Bath.2 He soon found, however, that Hertz had performed even more striking experiments on electromagnetic waves in Germany, and Lodge presented his own work simply as a confirmation of Hertz’s.
Lodge continued to work on lightning protection, working with Alexander Muirhead to patent and market an arrester for use on telegraph and power lines, and in 1892 publishing a book on Lightning Conductors and Lightning Guards that brought together his previous writings on the subject.3 Eventually he and others recognized the deficiencies in his experimental model of lightning, in particular the fact that storm clouds (unlike tea trays) do not act as connected conductors, and their discharges, though very sudden, are not generally oscillatory. But while Lodge’s work on electrical discharges was rooted in the practical problem of lightning protection, its real value lay elsewhere, in the scientific evidence it provided for the existence of electromagnetic waves, and in the eventual use of those waves for wireless telegraphy. Lodge’s work on wireless telegraphy did not grow out of pure undirected scientific research, nor did it grow out of a deliberate effort to produce a wireless communications system. Instead its development followed an ‘alternative path’, starting in one technological context and ending in a quite different one, passing along the way through realms of scientific experiment and theory.
Bruce J. Hunt
1Symons, George James, ed., Lightning Rod Conference (London: E. & FN Spon, 1882). [back]
2Oliver Lodge, ‘On the Theory of Lightning Conductors’, Philosophical Magazine, 26 (1888): 217-230. [back]
3Oliver Lodge, Lightning Conductors and Lightning Guards (London: Whittaker and Co, 1892). [back]