Kater, Henry

(b. Bristol, England, 16 April 1777; d. London, England, 26 April 1835)

geodesy

Although his formal scientific background was limited, Kater, the son of a bakery proprietor, rose to eminence in the Royal Engineers and generally in the world of British science. He was encouraged by his father to become an attorney, but after his father’s death in 1794 he abandoned his legal training and served with the British army in India, where he assisted William Lambton in surveying a region of Madras.

His higher education was confined to a brief period, when he was thirty-one, at the Royal Military College at Sandhurst. Kater’s most significant scientific contributions consisted of improvements in geodetic instruments, refinements of geodetic measurements, and in the standardization of weights and measures. After 1815, when he was elected a fellow of the Royal Society, he became active in the society’s affairs; he served on its council and as vice-president, was the first scientist to become treasurer, and won its Copley Medal in 1817 for his pendulum experiments.

On the basis of the principle enunciated by Huygens that the centers of suspension and oscillation are interchangeable, Kater devised a reversible pendulum (which became known as “Kater’s pendulum”) with knife edges accurately adjusted to lie at the conjugate points. By using the distance between these points as the “length” in the formula for a simple pendulum, he was able to determine with great accuracy the length of a pendulum beating seconds under specified conditions. He thereby obtained accurate values for g, the acceleration due to gravity, at several stations of the Trigonometrical Survey of Great Britain and estimated the ellipticity of the earth. Kater performed these experiments as a member of a committee appointed by the Royal Society in response to a request by the governmnet for assistance in standardizing weights and measures.

He also contributed to the improvement of telescopes by devising floating collimators, and in 1821 he reported the appearance of volcanic action on the moon. His experiments on the relative illuminating powers of Cassegrainian and Gregorian telescopes led him to conjecture on the nature of light (1813). It was one of his rare ventures into the realm of theory. The German astronomer Wilhelm Olbers, attempting to account for the darkness of the night sky, cited Kater’s reports to support his belief that space is not perfectly transparent.

BIBLIOGRAPHY

I. Original Woeks. The papers in which Kater described his pendulum experiments are “An Account of Experiments for Determining the Length of the Pendulum Vibrating Seconds in the Latitude of London,”in Philosophical Transactions of the Royal Society, 108 (1818), 33–102;and “An Account of Experiments for Determining the Variation in the Length of the Pendulum Vibrating Seconds, at the Principal Stations of the Trigonometrical Survey of Great Britain,” lbid., 109 (1819), 337–508. The papers cited by Olbers are “On the Light of the Cassegrainian Telescope, compared with that of the Gregorian, “ibid., 103 (1813, 106–212; and “Further Experiments on the Light of the Cassegrainian Telescope compared with that of the Gregorian,” ibid., 104 (1814) 231–247, A list of many of Kater’s publications is given in the Royal Society’s Catalogue of Scientific Papers, 1800–1863. III (London. 1869). He also wrote, in collaboration with dionysius Lardner, A Treatise on Mechanics (London, 1830), contributing the chapter “On Balances and Pendulums.”

II. Secondary Literature. Many of Kater’s papers are summarized in Abstracts of the Papers. Royal Society of London, I (London, 1832), II (London, 1833), and III (London, 1837). The fullest biographical articles on Kater are in Dictionary of National Biography and Charles Knight’s The English Cyclopaedia, Biography, III (London, 1856.

Harold Dorn