Fifteen Eighty Four

When I want to introduce people to the nineteenth-century polymath John Herschel (1792–1871), sometimes it’s difficult to know where to begin. There are simply so many possible ways to start:

• He was son of the world’s most famous astronomer, who himself became the first person to survey the entire sky telescopically, with these surveys ultimately resulting in the NGC numbers by which deep sky objects are still known today.
• He was famous on the international stage as the ostensible discoverer of life on the moon as subject of the “Great Moon Hoax,” the greatest astronomical hoax of all time.
• He was the photographic pioneer who coined the terms “negative” and “snapshot.”
• He was author of the first modern work on the philosophy of science, A Preliminary Discourse on the Study of Natural Philosophy, which shaped the careers of subsequent generations of scientists, including Charles Darwin.

He was widely perceived as the scientific heir to Isaac Newton, following in his footsteps as master of the mint and ultimately buried in his shadow in Westminster Abbey.

And these possible starting points don’t even touch on his popular textbooks, his travels, his role in reforming the Royal Society and founding the Royal Astronomical Society and the Analytical Society, his research in optics, geology, or chemistry, and his efforts to overhaul British mathematics in the early 1800s. In sum, John Herschel was easily the most important figure in the nineteenth-century scientific community, someone who shaped both the content and practice of science in the very period in which it was being transformed from natural philosophy to take on many of the attributes of modern science.

One of the things that makes it difficult to easily encapsulate John Herschel’s career is that he was of the last generation of natural philosophers (not yet called “scientists”—though the term was coined in his lifetime) who could be a scientific authority as a generalist instead of specializing as an astronomer, geologist, chemist, or physicist. The multifaceted nature of Herschel’s work has long resisted a comprehensive treatment. Besides two brief biographies (one privately published by the Herschel family and the other in the 1970s that the author himself refers to as a “sketch”) and my previous study of Herschel’s astronomical career, until now there has been no book-length study synthesizing Herschel’s scientific and mathematical work. On the other hand, the extend of Herschel’s work and interests makes him an ideal subject for the latest Cambridge Companion.

Herschel was son of William Herschel, famous for his surveys of nebulae and star clusters and discoverer of the planet Uranus. After early mathematical work, focused on developing advanced algebraic methods to displace the older geometrical approaches to calculus dominant in England, John Herschel took up his father’s work of surveying the skies. After his parents’ deaths, this project ultimately carried him to the far reaches of the British empire, where he spent four years at the Cape of Good Hope in South Africa, extending his surveys to the skies of the southern hemisphere. Along the way, Herschel helped establish that binary stars were gravitationally bound, established naming conventions for the moons of the outer solar system, invented a device for measuring solar energy, and wrote popular textbooks that shaped Victorian ideas on the practice of astronomy and the nature of the stars and heavens.

In addition, Herschel pursued chemical and optical research, in particular investigating the new art of photography and developing several methods of fixing photographic images, including discovering the chemical fixer that became the basis for developing film. He also created the cyanotype, the method of developing that formed the basis and characteristic hue of architectural blueprints.

Yet these scientific accomplishments were only a portion of his wider influence. Through his copious correspondence, his work on various scientific committees, boards, and societies, and significantly through his Preliminary Discourse—his great introduction to the methods and motives of science—Herschel shaped scientific practice throughout his career. A portion of this influence was simply his example, eschewing controversy and cultivating international scientific cooperation in the wake of the Napoleonic Wars. Part of this was also his work to reform learned societies that he felt were based on privilege and position rather than scientific merit—in particular, the Royal Society. This particular reforming effort culminated with Herschel running for president of the Royal Society against the brother of the king in what many saw as a confrontation between scientific merit and aristocratic privilege for control of science. That Herschel lost and yet the Duke ultimately implemented many of the reforms Herschel had urged only increased Herschel’s credibility.

As this brief outline shows, there is much to explore regarding Herschel’s significance for the history of science, and it has been a pleasure to work with the contributors to the Cambridge Companion to John Herschel to provide this scholarly companion to Herschel’s life and career. The chapters include studies of Herschel’s particular scientific contributions—his photography, geology, mathematics, and astronomy—as well as others that focus on his biography—such as his upbringing, the influence of both his father and his famous aunt, Caroline Herschel, and his time at the Cape. Other chapters discuss Herschel’s influence, as a working scientist, a political reformer, and as author of the Preliminary Discourse. My deepest appreciation to those who made this volume what it is: the first comprehensive, scholarly treatment of the greatest natural philosopher of the nineteenth century.