The Transatlantic Slave Trade: A New Census

Abstract

cc i 0 intellectual passions are stronger than those involved in achieving precision, standards and conventions. The stable results of those struggles appear matter-of-fact, but realising them is an emotional, political and messy business. Scientific agreement on the value of the last decimal place, the last second of arc, the starting meridian of longitude, the relative accuracy of naked-eye or telescopic sights on the sextant, the value of a foot, ounce and pound, and the calibration of the thermometer mobilises passions and political energies on a heroic scale. Those who mean to achieve precise scientific representations and to make them widely credible must, for these reasons, be as good at social engineering as at observing, recording and measuring. Knowledge of the apparent and proper motions of a comet through the sky or of the duration of a solar eclipse, for example, were collective accomplishments, and so, too, were reliable star-charts and maps of geomagnetic variation. To produce such things, and to make them credible, you had to know something not only about the natural world but also about other observers, their skill and their integrity. You had to know who was a skilful and honest observer, you had to get them to communicate their observations, you had to bring these observations together in one place, and represent them in such a way that they could circulate robustly in a range of scientific and practical communities.1 These words come from a review of a biography of Edmond Halley. We know Halley's name today from the comet, but his importance goes much beyond that. It was owing to him that Newton published the Principia, something that Newton acknowledged in his preface; Halley prepared charts, tables, and maps of stars, comets, and tides; he invented isolines; he constructed life tables and has been called the father of modern life insurance. He even invented a diving bell to salvage a sunken treasure ship for the Royal African Company and went down in it himself.