Marketing Longitude: Clocks, Kings, Courtiers, and Christiaan Huygens

You are, Sir, among the few men for whom this book was made, and who I hope to have as readers; because of this I am obliged to send you this example.

—Huygens to Pierre Bayle, 17 February 1690

Introduction: The Horologium of 1685

In 1665 Christiaan Huygens, one of the most famous Dutch mathematicians, made an unusual appearance on the docks in Amsterdam. His purpose was to host a seminar on the use of his newly invented pendulum clock, and his audience consisted of sea pilots and sailors who could use the marine timekeeper on their ships. In a small room along the waterfront Huygens detailed the clock's mechanisms, the proper mounting of the instrument, and the manner in which time could be determined at sea. We can only imagine the scene: the upper-class gentleman with his elegant clock, describing for seasoned sailors how the determination of longitude was now possible; the sailors listening dubiously to the promise of an expensive new instrument that could forever change their navigational techniques. Predictably, the workshop was less than appreciated. The sailors hardly disguised their absence of faith in the instrument, as Huygens explained to his father, the renowned Dutch poet and diplomat Constantijn Huygens: "Being in Amsterdam I conferred with several of our seamen, as well as with . . . those who understand navigation; they cannot deny [the clock's] utility. However, I have noticed how slow and unwilling our seamen are to acknowledge something new which has such obvious utility."¹ Huygens quickly realized that personal appearances alone would not make marine sailors accept his clock. But his meeting with a group clearly outside of his normal community of mathematicians and natural philosophers provides an excellent example of his attempts to reach different audiences with his work.

In what follows, I will explore the way Huygens actively cultivated heterogeneous audiences for his published works by tailoring them to particular readers and distributing them in strategic ways. Analyzing his authorial intentions in this manner not only enhances our reading of these important works in the history of science, it also helps us to understand how mechanics permeated cultural boundaries in early modern Europe. Though Huygens published across the spectrum of scientific disciplines, with works on mathematics, mechanics, natural philosophy, astronomy, and optics, I focus here on his three publications related to the pendulum clock: the Horologium of 1658, the Kort Onderwijs (Brief Instructions) of 1665, and the Horologium Oscillatorium of 1673.² The first two were written when Huygens was an independent scholar in the Low Countries, the third while he was a member of the French Académie Royale des Sciences, under the patronage of Louis XIV and Jean-Baptiste Colbert. Thus the intellectual and institutional contexts in which the works were composed varied, but they had a common objective.

Huygens's aim was to produce a pendulum clock that was accurate enough to determine longitude at sea, and he had begun working on the problem in 1656.³ After developing and testing several prototypes he had a model that he felt would solve the problem, and in 1658 he made his design public in his Horologium. By that time Huygens had already shared diagrams of his new clock with a French correspondent, the councillor to the king of France, Jean Chapelain, but upon realizing that he had a marketable instrument, he asked Chapelain to refrain from sharing the design: "Not having at present the time to respond as I would like to your obliging letter, I offer here only a few lines in order to ask you not to communicate to anyone the construction of my clock, which, while vague enough, could be understood by someone."⁴ Chapelain promised to keep the information private, agreeing that disclosure might cost Huygens priority. The work was finished in mid-June, and Adriaan Vlacq, a well-known Dutch printer, published it in early September 1658.⁵

The Horologium was a simple quarto, only fifteen pages including the dedication. Its purpose was clearly to make the technology and its inventor known. Huygens sought priority not only for himself but...