The Transit of Venus Enterprise in Victorian Britain (review)

From time to time, scientists and their national institutions find themselves symbiotically entangled. Nothing exposes the strains and strengths of these relationships like a research problem with an expensive solution proclaiming ties to the national interest. For Victorian astronomers, one such problem was the old and seemingly intractable challenge of determining the true solar parallax, or distance separating the earth and sun. Like all long-standing problems, measuring the solar parallax spawned a number of creative solutions. Using documents produced by participants in a large-scale, government-subsidized, problem-solving science project, Jessica Ratcliff offers an engaging and provocative contribution to our understanding and appreciation of the organizational, executive, and analytic skills involved in such an undertaking.

Ratcliff focuses on the ingenious, but costly, approach proposed by Edmond Halley in 1716: carefully observing and timing events from different latitudes during transits of the sun by Venus. Halley's method was first implemented with limited success in 1761 and 1769. Another pair of the rare events were due to occur in 1874 and 1882. Despite the cost and risk involved, talk of mounting multiple expeditions to try Halley's method anew, this time with modern tools and expertise, began in the late 1860s.

The nearly seventy-six-year interval that separates Comet Halley's periodic returns is resonant with the outer limits of human life expectancy that require personal experiences to be passed, like runners' batons, across generations otherwise separated by chasms of imagination and memory. These experiences amplify and gloss the volumes of data diligently recorded during each historic apparition. The current syncopated 122, 8, 105, 8, 122, 8–year rhythm of Venus's transit events has allowed for no such living bridge, leaving expedition planners in the same situation as soldiers going into battle with all the latest equipment, but mentally and strategically prepared to fight the last war.

Although the Victorians possessed a palette of new and presumably improved though untested mensurational tools and technologies, their expeditions' results did not meet the expectations of participants and patrons alike. Perceived as failures and lacking the eighteenth-century efforts' nostalgic glamour and romance, the nineteenth-century expeditions were quietly and unceremoniously swept out of public view. Nevertheless, as Ratcliff shows, there are valuable lessons to be learned here about the emergence of modern large-scale scientific projects. She has gleaned quite a harvest from the published and unpublished records generated before, during, and after these expeditions. By restoring participants' long-dead voices, she lets them tell the story of their ardent quest in the name of tradition, national interest, and precision to eliminate, once and for all, the uncertainty that still muddled measures of this crucial celestial yardstick.

The nineteenth-century transit events attracted global attention. Some nations' astronomers took advantage of the rare opportunity to investigate other attending phenomena. In 1874, for example, Italian astronomer Pietro Tacchini searched for evidence of a Venusian atmosphere. Although Ratcliff touches on the collaborative/competitive tension among expedition-organizing nations, she restricts her discussion to those involving efforts to measure parallax, and for the most part, she focuses on operations within the British transit missions. Of special interest is the role of the Admiralty as both a sponsor of and participant in the expeditions. As Ratcliff points out, many of the skills and practices associated with scientific astronomical observation were routinely used by military personnel to maintain Britain's hegemony on the seas. The Admiralty's budget and global presence made it a natural and economical resource from which civilian scientific institutions might seek the funds, materiel, and expertise they needed to plan expeditions beyond their means. For centuries, advances in astronomical science had undergirded improvements in navigational practice. But by the second half of the nineteenth century, that mutually beneficial arrangement deteriorated as the needs, interests, and conveniences of navigators and astronomers began to diverge. The love-hate relationship between the Admiralty and expeditionary civilian astronomers is a topic worth further investigation...