The World Measured: Science Comes of Age

1657-1700

In the age of Isaac Newton, it seemed that anything could be ­collected, measured or categorized as Western science sought to define the world and all of nature.

By unmooring the Earth, the ideas of Copernicus, Galileo, and Kepler contradicted literal readings of Genesis, but they accounted for celestial appearances with unmatched precision. Given an accurate model of the solar system and the corresponding laws of planetary motion, astronomers could successfully predict the sky’s configuration decades hence. From these calculations, they could create astronomical tables detailing planetary configurations over a known point on Earth, calculations that would remain accurate for several decades. Surveyors, comparing their own observations with predictive measures taken from these veritable lighthouses, could identify their own positions accordingly. And they could do so independently, from points around the globe.

Accelerated by the wrenching political transition from the Late Medieval to the cusp of Modernity, cartography had advanced fundamentally. Where European mapmakers had once relied on metaphysical speculation inherited from ancient empires, they were now working from a basis supported by telescopic observation, mapping regions that had never been mapped, on a scale that was unprecedented, and doing so with once-inconceivable resolution. Within this new frame of reference, the outlines of the world began to change—on maps themselves, and in the minds of their readers. As the Scientific Revolution gained ground, knowledge of the relative positions of land and sea evolved from a matter of open question to one of established fact.

The Peace of Westphalia (1648) ended the Eighty Years’ War between Spain and the Netherlands, providing the Dutch Republic with its complete independence. It also ended the Thirty Years’ War that had devastated the Holy Roman Empire. Above all, it established the principle of the sovereign state, one subordinate only to its own king, free from political interference by any external authorities, and secure enough to grant private religious freedom to its subjects. Dismissing outraged condemnation from Rome, its signatories created the first modern nations. Like the contemporary maps derived from a heliocentric understanding of the sky, these arrangements provided a new foundation for political life–one that would come to fruition in the eighteenth century Enlightenment as individuals began thinking of themselves as citizens, rather than subjects, and forcefully demanding direct involvement in their own governance.

Historical Figure

Halley

Rationalizing the World

Edmond Halley (1656–1742) was an English astronomer, geog­ra­pher, cartographer, and physicist whose career encompassed a broad range of Enlightenment-era developments and epitomized the spirit of the age. He traveled widely, advancing the scope of astronomical and terrestrial charts to great effect. His investi­ga­tions of Kepler’s third law precipitated the publication of Isaac Newton’s Principia (1687), which introduced the concept of quan­ti­fied force to the study of nature. After becoming England’s Astronomer Royal, Halley made fundamental contributions to the challenge of determining longitude at sea.

In 1703 Halley was appointed the Savilian Professor of Geometry at Oxford, and he published his Synopsis Astronomica Cometicae [A general view of astronomical comets] in 1705. Postulating that the comet he’d seen in 1682 was periodic and was the same as the one observed by Kepler in 1608, Halley projected its ellipse, accounted (roughly) for the effects of Jupiter’s gravity, and ­estimated—accurately—that it would return in 1758. The comet’s timely reappearance was a dramatic testament to the value of Newton­ian mechanics and their foundation in the law of elliptical motion. The comet bears Halley’s name and secured his lasting fame.

Appointed Astronomer Royal in 1720, Halley was stationed at the Observatory in Greenwich for the last twenty-one years of his life. Between 1721 and 1739 he conducted a complete lunar survey of the Saros cycle, the eighteen-year period required for the Moon, Earth, and Sun to realign themselves in any given arrangement. By 1731 he’d tabulated enough results to asses the accuracy of Newton’s lunar theory and to quantify a consistent margin of error. The incorporation of Newtonian mechanics into the observational record proved especially useful in the refinement of lunar observa­tions and the precise accounting of lunar and planetary passages. In 1766 the Royal Observatory published the first nautical almanac that was accurate enough to permit mariners to use the lunar-distance method in approximating longitude at sea.