Probing the Sky with Radio Waves: From Wireless Technology to the Development of Atmospheric Science by Chen-Pang Yeang (review)

Dot-dot-dot, “S” in Morse code, were the three beeps heard round the world. Probing the Sky is the story of the discovery of the ionosphere through its theoretical construction, mathematical description, and intrusive presence in the continuous development of radio as wavelengths got shorter, signals stronger, and code gave way to voice. Starting with Marconi’s famed demonstration of transatlantic radio and Hertz’s theoretical development of the properties of radio waves, Chen-Pang Yeang’s book performs several feats of heavy intellectual lifting to show how the theoretical and practical united to give not only the science of radio waves but also atmospheric science. As with all the best work in the history of science and technology, Yeang shows how the formation of the scientific and technical realms of radio also shaped, and were shaped by, that part of nature radio supposedly traversed, the atmosphere. “Far from being transparent, that medium is usually complex, [and] entangles itself with imaging and measuring” (p. 3). The strength of Yeang’s work is that he confronts the complexity of theoretical equations, radio circuit diagrams, and atmospheric variables head-on to not only disentangle the story for the reader, but to deeply explain the varied and competing ideas and practices of early radio propagation science that led to the discovery of the ionosphere.

The overarching “Humboldtian” approach (p. 5) returns again and again as ever-larger endeavors in the 1900s, 1920s, and 1930s attempt to plot and mass sufficient data to draw predictive conclusions about the properties of radio waves. Like radio, Yeang’s book crosses institutional, disciplinary, and national borders. A nice element of the narrative is that it smoothly and easily flows between national efforts. A hallmark of twentieth-century science and technology is its international character, and Probing the Sky is a model for this kind of large-scale historical work, as it turns from radio amateurs to the U.S. Naval Research Laboratory, to German and British mathematical physicists. Though the industrial side of the story of radio is given rather less space than the “scientific” aspects, nonetheless the multilayered institutional approach makes Yeang’s book a valuable addition to the literature on not just radio, but early-twentieth-century science and technology. The ongoing development and debate over theory is privileged but also punctuated by other official experiments such as the American navy’s early radio measurements, and a terrific chapter 5 detailing the contribution of the radio amateurs (significant, even though they were organized through the American Radio Relay League and corralled into standardized productivity through a series of double-blind field trials). It was through the parallel process that “propagation studies were beginning to evolve into atmospheric physics” (p. 146).

The book is a wealth of technical details both mathematical and technological. Yeang is adept at switching back and forth between theoretical conceptualizations and practical technological experiments and devices. The detailed amalgamation of fine theoretical moments and finicky technical points conveys a story about a technoscientific endeavor that firmly demonstrates how interconnected the worlds of science and technology were in the realm of radio. It is notable, however, that while the theoretical equations are fully explicated by, and integrated into, the overall narrative, the technological circuits remain mere figures. While the text concerning H. M. Macdonald’s work in the theoretical physics of the propagation of radio waves runs from page 27 to 31, the description of figure 3.2 on page 59 is relegated to a long footnote over pages 57–60. Yeang, like his mathematical physicists, emphasizes the theoretical over the technological. Unquestionably, I tip my hat to an author with demonstrable mastery over the equations of the mathematical physicists; Yeang ably describes the evolving theoretical models of radio waves between the 1890s and the 1930s. Some readers will no doubt be daunted by their frequent...