Turning point

William Tobin has written a biography of Léon Foucault, whom time and science forgot. The fact that Foucault has been overlooked is obvious from the book’s subtitle and the defensive preface. Clearly Tobin thought it necessary to inform the reader of Foucault’s major scientific accomplishment, namely his proof that the Earth rotates. He also makes a convincing case that Foucault and the scientific world in which he worked mattered. However, the book is far less satisfactory or convincing as a biography.

Divided chronologically into 17 chapters with four appendices, this handsomely illustrated book takes the reader inside the faction-ridden, status-conscious world of international science in the mid-19th century. Born in Paris in 1819, Jean-Bernard-Léon Foucault grew up there and in Nantes. He began – but did not complete – medical training and instead started using photography for astronomy. He later experimented with the electric arc light. During the mid-1840s Foucault worked as a scientific reporter for the respected Journal des Débats, where his interests shifted from the technological and the medical to the more scientific. He received his doctorate in 1850 from the University of Paris for devising experiments debunking the corpuscular theory of the emission of light.

The next brief phase of Foucault’s career was when he explored the movement of the Earth; this proved to be the most productive period in terms of recognized contributions to science. Tobin briefly traces Foucault’s 1851 experiments to demonstrate the Earth’s motion using pendulums and then delineates the spread of “pendulum mania” across the world. In 1852 Foucault successfully perfected the gyroscope to confirm the Earth’s rotation.

As a scientific spectacle, the pendulum strongly affects anyone who has witnessed one in motion (see “Seeing our own world rotate” by Robert P Crease Physics World July 2003 p16). Indeed, the image of this experiment became the centrepiece of Umberto Eco’s 1990 best-seller Foucault’s Pendulum.

The rest of Foucault’s career was one of solid accomplishment but no other major breakthroughs. Like so many other scientists of the time, he was held back by his mediocre mathematical skills. Foucault’s insights came instead from his expertise at figuring out experimental or technological means of illustrating a scientific problem; his best science was almost always applied.

In the aftermath of his work on the pendulum and the gyroscope, Foucault found – through the patronage of Emperor Napoleon III – official employment as physicist for the Paris Observatory in 1855 and the Bureau of Longitudes in 1862. Three years later he was elected to the Academy of Sciences. This era saw Foucault experiment with induction coils, circuit-breakers, heliostats, governors for steam engines and the design of large-scale telescopes. He also made an excellent approximation of the speed of light. Foucault died prematurely in 1868, aged 48.

Tobin, who is an astronomer at the University of Canterbury in New Zealand, has extensive experience of working in (and directing) observatories. This background as a professional scientist – rather than a biographer or historian – has its strengths and weaknesses as far as this book is concerned. Judged as a work of popular physics, Tobin does an admirable job, clearly explaining in a lively style many relatively complex processes, concepts and gadgets. Professional historians will, however, be troubled by his use of sources, particularly his willingness to take contemporary comments at face value. The author frequently uses phrases like “Foucault must have felt…” or “we can sense that…” to fill in the gaps in his evidence. Numerous errors of historical fact, especially in the early chapters, also do not inspire confidence in his non-scientific judgments.

The major problem with this book is that the reader does not really get a sense of the man behind the science that fascinates Tobin so deeply. We learn that Foucault was independent-minded, prickly, bad at mathematics, and emotionally and mentally fragile.

He liked the company of women, enjoyed drinking coffee, “probably did not smoke”, and made many more friends than enemies. But lurking beneath these broad judgments and statements of fact, the essence of the individual does not emerge from this book.

The trouble seems to be fragmentary documentation rather than any negligence on the part of the author. Still, the lack of personal touches and intimate thoughts – in an era in which most biographies are rife with them – is extraordinary. On those occasions where the links between personality and science can be drawn (page 129), the narrative is greatly enriched. It is worth noting that Tobin himself is fully aware of this flaw (pages 278-283).

Tobin’s account is most successful in its depiction of mid-19th-century science and its growing professionalization. There are long and detailed descriptions of all sorts of experiments and the development of various mechanical devices of greater or lesser importance. The narrative is clear and usually free of jargon. Readers will not need much prior scientific knowledge to follow the text. But without more editorial guidance – or an in-depth understanding of the development of the history of science and technology in this period – it is hard to separate the wheat from the chaff in Tobin’s exuberance for his subject.

For those without this background, some of the depictions of outmoded procedures and instruments can be more than a little dry. Evoking a scientific world that no longer exists is a difficult task, and Tobin has succeeded well at it. Making us care about an individual and how his life exemplifies an era – while placing that individual’s accomplishments in a wider context – are different missions that await another swing of the pendulum or perhaps a further spin of the gyroscope.