THE NINETEENTH CENTURY

In 1870, the British Royal Society in London, England witnessed a thought-provoking demonstration given by natural philosopher, John Tyndall. Tyndall, using a jet of water that flowed from one container to another and a beam of light, demonstrated that light used internal reflection to follow a specific path. As water poured out through the spout of the first container, Tyndall directed a beam of sunlight at the path of the water. The light, as seen by the audience, followed a zigzag path inside the curved path of the water. This simple experiment, illustrated in Figure 1.1, marked the first research into the guided transmission of light.

Figure 1.1: John Tyndall's Experiment

William Wheeling expanded upon Tyndall's experiment when, in 1880, he patented a method of light transfer he called "piping light." Wheeling believed that by using mirrored pipes branching off from a single source of illumination, i.e. a bright electric arc, he could send the light to many different rooms in the same way that water, through plumbing, is carried throughout buildings today. Due to the ineffectiveness of Wheeling's idea and to the concurrent introduction of Edison's highly successful incandescent light bulb, the concept of piping light never took off until late in the 20th century when several commercial systems were introduced. Wheeling's ideas were about a century ahead of the technology required to make "piping light" feasible.

That same year, Alexander Graham Bell developed an optical voice transmission system he called a photophone. Like Wheeling's method...